The factors that affect the chemical reaction rate in junior high school chemistry are as follows: 1. Temperature 2. Concentration 3. Catalyst 4. Contact area

The factors that affect the chemical reaction rate in junior high school chemistry are as follows: 1. Temperature 2. Concentration 3. Catalyst 4. Contact area

Temperature: high temperature in summer, food is easy to deteriorate
Concentration: the wood with embers Reburning in the oxygen bottle
Catalyst: H2O2 Decomposition
Area: crushing large pieces of fuel makes it easier to burn

For example: the influence of temperature on the existence of biological life?

Environmental temperature directly or indirectly affects the growth and development, living conditions, reproduction and distribution of organisms. The growth and development of any organism requires certain temperature conditions. Plants: the temperature should be appropriate, otherwise it will affect the germination of seeds, which is not conducive to the growth of plants. Different kinds of plants need different temperatures for growth

Examples of cherishing time
In life~

Shakespeare cherishes time
Shakespeare was a great English dramatist and poet in the Renaissance 400 years ago. He was born in 1564 and died in 1616. He began to write when he was 24 years old. In just 20 years, he wrote 37 plays, 2 long poems and 154 sonnets, which left great spiritual wealth to later generations, In China, many of Shakespeare's plays are also well-known. To commemorate him, many countries have issued stamps. The attached picture is "commemorating the 400th anniversary of Shakespeare" stamp issued by Hungary in 1964
Marx called Shakespeare "one of the greatest geniuses of mankind". It is true that Shakespeare is very talented, articulate, natural and unrestrained, and has the ability to perform. However, his success is more from his diligence. Shakespeare has a famous saying: "those who give up time, time also gives up him". He cherishes time very much, Shakespeare studied in a local "literature school" when he was young. The school was very strict, so he received a lot of basic education. After six years in school, he squeezed out time to read thousands of literature and art books in the school library, and recited a lot of poems and wonderful dialogues in plays
Shakespeare loved drama when he was young. He was born in a wealthy family. His father was the mayor of the town. He liked to see plays and often invited some troupes to perform in the town. Every time, Shakespeare was fascinated by them. When there was no performance in the town, he called on the children to imitate the characters and plots in the play. He also wrote, directed and acted in the town, He was a soldier, an apprentice, a bricklayer, a small worker, an aristocrat's housekeeper and a village teacher. In the process of supporting his family, he made a careful observation of all kinds of characters and recorded their personal dialogues, Shakespeare came to London when he was 22 years old. His strong pursuit of drama led him to find a job as a doorman in a theater. At first, he just led horses and cars to the dignitaries. Later, he used the tips he earned to transfer to some children to help him finish his work, but he took the time to watch the performance in the theater, Shakespeare began to play a supporting role in the performance. He was very happy about this, because he could watch the performances of the actors more closely on the stage. Later, Shakespeare Became a "libretto". Hiding in the props, he did his job well, When Shakespeare Became a regular actor, plague began to spread in Europe. Thousands of people died and the theater was forced to close down. The owners and actors went out to escape the plague, but Shakespeare chose to stay behind to guard the theater. In the two years of extreme economic depression, Shakespeare seized the time to read a lot of books, He sorted out his notes of various periods, revised several plays, and started the creation of new plays. When the British economy revived and the performance was booming again, Shakespeare's plays were launched, and he himself became the most outstanding actor
Shakespeare's success lies in his ability to cherish every bit of time for study, thinking and creation. His plays originate from life and are higher than life. They are not only beautiful in words, rich in language and distinctive in characters, but also full of rhythm in dialogues, which makes it easy for the audience to feel empathy from their hearts

If AB = AC, = C if and only if a is a zero matrix, how to prove it
How to prove it? I've thought about it for many days,

Let's say a = diag {1,0,0}, B = diag {0,1,0}, C = diag {0,0,1}

On the problem of five cosine theorem in senior two mathematics
It is known that the triangle ABC satisfies the condition that the angle B is 60 degrees, ab = 3, AC = root 7 to find the length of BC
A2, B1, C1 or 2 d have no solution

Choose C
Square of AC = square of AB + square of BC - 2Ab * BC * CoSb
The solution is BC = 1 or 2

Give examples of the key points and error prone points of the first chapter of mathematics compulsory 2. That is, conceptual problems or problem-solving skills are OK.

The first chapter is a preliminary study of solid geometry
1. Structural characteristics of column, cone, table and ball
(1) Prisms:
Geometric features: two bottom surfaces are congruent polygons parallel to corresponding sides; side and diagonal surfaces are parallelogram; side edges are parallel and equal; section parallel to bottom surface is congruent polygon with bottom surface
(2) Pyramid
Geometric features: the side and diagonal planes are triangles; the section parallel to the bottom is similar to the bottom, and its similarity ratio is equal to the square of the ratio of the distance and height from the vertex to the section
(3) Prisms:
Geometric features: ① the upper and lower bottom surfaces are similar parallel polygons; ② the side surfaces are trapezoids; ③ the side edges intersect the vertices of the original pyramid
(4) Cylinder: definition: it is formed by the rotation of the line on one side of the rectangle and the rotation of the other three sides
Geometric features: ① the bottom is a congruent circle; ② the generatrix is parallel to the axis; ③ the axis is perpendicular to the radius of the bottom circle; ④ the side expansion is a rectangle
(5) Cone: definition: a right triangle with a right side as the axis of rotation, rotating a circle
Geometric features: ① the bottom is a circle; ② the generatrix intersects the apex of the cone; ③ the side expansion is a sector
(6) Round platform: definition: it is formed by one circle of rotation with the vertical of right angled trapezoid and the waist at the bottom as the rotation axis
Geometric features: ① the upper and lower bottom surfaces are two circles; ② the side generatrix intersects the vertex of the original cone; ③ the side expanded view is an arch
(7) Sphere: definition: a geometric body formed by a semicircle surface rotating one circle with the straight line of the semicircle diameter as the rotation axis
Geometric features: ① the cross section of the sphere is a circle; ② the distance from any point on the sphere to the center of the sphere is equal to the radius
2. Three views of space geometry
Three views are defined: front view (the light is projected from the front of the geometry to the back); side view (from left to right); and
Top view (top down)
Note: the front view reflects the height and length of the object; the top view reflects the length and width of the object; the side view reflects the height and width of the object
3. The visual drawing of space geometry
The characteristics of oblique two survey drawing method are as follows: 1. The line segment which was originally parallel to X axis is still parallel to X and the length is not changed;
② The original line segment parallel to y axis is still parallel to y, and its length is half of the original
4. Surface area and volume of cylinder, cone and platform
(1) The surface area of a geometry is the sum of the areas of its faces
(2) Surface area formula of special geometry (C is the perimeter of the bottom, h is the height, oblique height, l is the generatrix)
(3) Volume formula of cylinder, cone and platform
(4) The surface area and volume formula of sphere: v =; s=
There are also other chapters
1、 Straight line and equation
(1) The inclination angle of a straight line
Definition: the angle between the positive direction of the x-axis and the upward direction of the straight line is called the inclination angle of the straight line. In particular, when the straight line is parallel to or coincident with the x-axis, we specify that its inclination angle is 0 degree. Therefore, the value range of the inclination angle is 0 °≤ α＜ 180 °
(2) The slope of a straight line
① Definition: the tangent of a straight line whose inclination angle is not 90 ° is called the slope of the straight line. The slope of the straight line is usually expressed by K. that is, the slope reflects the inclination of the straight line and the axis
At that time,; at that time,; at that time, there was no existence
② The slope formula of a straight line passing through two points:
Pay attention to the following four points: (1) at that time, the right side of the formula is meaningless, the slope of the straight line does not exist, and the inclination angle is 90 °;
(2) K has nothing to do with the order of P1 and P2; (3) the later slope can be obtained directly from the coordinates of two points on the straight line instead of the inclination angle;
(4) The inclination angle of a straight line can be obtained by calculating the slope of the coordinates of two points on the line
(3) Linear equation
① Point oblique: the slope of the straight line is k, and it passes through the point
Note: when the slope of the line is 0 °, k = 0, and the equation of the line is y = Y1
When the slope of a straight line is 90 degrees, the slope of the straight line does not exist, and its equation can not be expressed in the form of oblique point. But because the abscissa of every point on L is equal to x1, its equation is x = x1
② Oblique section: the slope of the line is k, and the intercept of the line on the Y axis is B
③ Two point formula: () straight line two points,
④ Cut moment formula:
Where the line intersects the axis at a point, and intersects the axis at a point
⑤ General formula: (a, B are not all zero)
Note: the scope of application of various equations is special, such as:
A line parallel to the x-axis: (B is a constant); a line parallel to the y-axis: (a is a constant);
(5) Linear system equation: that is, a line with a common property
（1） Parallel line system
A system of lines parallel to a known line (a constant that is not all zero): (C is a constant)
（2） Vertical line system
A system of lines perpendicular to a known line (a constant that is not all zero): (C is a constant)
（3） Straight line system passing through fixed point
(I) the system of lines with slope k: the line passes through a fixed point;
(II) the equation of the line system passing through the intersection of two lines is
(is a parameter), where the line is not in the line system
(6) Two lines parallel and perpendicular
When, when,
；
Note: when using the slope to judge whether a straight line is parallel or vertical, pay attention to the existence of the slope
(7) The intersection of two lines
intersect
The point of intersection coordinates is a set of solutions of the equations
The system of equations has no solution; the system of equations has innumerable solutions and coincidence
(8) The formula of distance between two points: let two points be in the plane rectangular coordinate system,
be
(9) Formula of distance from point to line: distance from point to line
(10) Distance formula of two parallel straight lines
Take any point on any line, and then convert it into the distance from point to line
2、 The equation of circle
1. The definition of circle: the set of points whose distance to a certain point in the plane is equal to the fixed length is called circle. The fixed point is the center of the circle and the fixed length is the radius of the circle
2. The equation of circle
(1) Standard equation, center of circle, radius R;
(2) General equation
At that time, the equation represents a circle. At this time, the center of the circle is and the radius is
At that time, it represents a point; at that time, the equation does not represent any graph
(3) The method of solving circular equation is as follows
Generally, the undetermined coefficient method is used: set first and then find out. Three independent conditions are needed to determine a circle,
We need to get a, B, R; if we use the general equation, we need to get D, e, f;
In addition, we should pay more attention to the geometric properties of the circle: for example, the vertical line of the string must pass through the origin, so as to determine the position of the center of the circle
3. Position relationship between line and circle:
There are three kinds of position relationship between line and circle: separation, tangency and intersection
(1) Let a line, a circle, and the distance from the center of the circle to l be;;
(2) The tangent line passing through a point outside the circle: ① K does not exist, verify whether it is true; ② K exists, set a point oblique equation, use the distance from the center of the circle to the straight line = radius, and calculate