Unit 3 of Chinese Book grade 6 Volume 1,

Words inventory reading and writing comfortable shelf reluctantly complain listening set off burly tear bad luck serious worry holy long solemn ceremony sorry to slip away mind asking absurd reputation give up wet heart to talk to oneself suffer sewing mend surprised reading notes disability thin generous Zhang Huang

Primary school sixth grade volume I language book accumulated over time, the first four units! Quickly tell me! I forgot to bring the language book, tomorrow will hand in homework!

Falling red is not a merciless thing, but turns into spring mud to protect flowers. (Gong Zizhen) the creation is silent but sentimental. Every time it is cold, you can feel the spring. (Zhang Weiping) tonight, you know the spring is warm, and the sound of insects is fresh and green. (Liu Fangping) when you hear the broken willows in this Nocturne, who can't afford to love your hometown. (Li Bai) lying in the sky, the clouds are still, I don't know that the clouds are all east with me. (Chen Yuyi) no

If the set {2, the square of a} intersects {2a-4,1,2,3} = {the square of 6A - the square of a - 6}, then the value set of real number a is?

It can be seen from the question that the intersection of two sets has only one element (the square of 6A - the square of a - 6)
Then we can deduce that the element is 2, because we can see from the known conditions that there must be element 2 in the intersection, and there is only one element, so the element must be 2
So 6A ^ 2-A ^ 2-6 = 2
By solving this equation, we can get that the solution is a = + (8 / 5) to the second power and a = - (8 / 5) to the second power
The set of a is (= + (8 / 5) to the second power, a = - (8 / 5) to the second power)
I don't know if it's your question or my calculation. I always feel that the answer is strange
But the method must be this one

The time ratio of passenger train from place a to place B and freight train from place B to place a is 2:3. The two trains leave from both places at the same time. When they meet, the passenger train travels 96 kilometers more than the train
Better not use the equation

The distance between the two places is 96 ± (3-2) x (3 + 2) = 480km
If you don't understand this question, you can ask,

Let {an} satisfy a1 + 3a2 +. + 3n-1an = n / 3 (n-1 is the power), n belongs to n *, and the general term formula of {an} is obtained. 2. Let BN = n / an,

A1 + 3a2 +. + 3 ^ (n-1) an = n / 3 multiply both sides by 3 to get: 3A1 + 9A2 + +3^nan=n.
The N-1 term is. 3A1 + 9A2 + +3^（n-1）an-1=n-1.
We want to reduce the two formulas to 3 ^ Nan = 1
an=3^(-n)

15 - 17 days and 23 hours to the end of the problem
If PQ is two simple propositions and the negation of P or q is a true proposition, then there must be_______
A and B are always two propositions. If a is a sufficient and unnecessary condition of B, then a is B_
It is known that set M = {(x.y) | x + y = 2} n = {(x.y) | X-Y = 4} then set M ∩ n is____

1. ˉ P and ˉ Q are true
2. Necessity is not sufficient
3. Is the intersection of two straight lines: (3, - 1)

1. A system of equations composed of two () equations and containing () unknowns is called a system of quadratic equations
2. A solution satisfying () in a system of linear equations of two variables is called the solution of the system of linear equations of two variables

1. A system of equations consisting of two (first-order) equations and containing (two) unknowns is called a system of binary first-order equations
2. A solution satisfying two equations in a system of linear equations of two variables is called the solution of the system of linear equations of two variables

The earth, the Milky way, the solar system, the universe, Asia and the moon

From big to small are the universe, the solar system, the Milky way, the earth, the moon and Asia

Solve the equation. 25X equals 20, x plus 35 equals 540, x minus 78 equals 808

25%x=20
x = 20 × 100 / 25 = 80
x+35%x = 540
135%x = 540
x = 540 × 100 / 135 = 400
x-78%x = 88
22%x = 88
x = 88 × 100/22 = 400

As for sliding friction, the following statement is correct: A has positive pressure, there must be sliding friction; B has sliding friction, there must be positive pressure
C the sliding friction is always perpendicular to the positive pressure on the contact surface
D only moving objects are subject to sliding friction
PS: the answer is BC. Please explain why BC is right and why the other two are wrong. Please be more detailed. Thank you!

Formula F = UN
A: On a smooth surface, although there is positive pressure, there is no sliding friction because the friction coefficient u is 0;
B: If the friction force is not equal to 0, then u and N must not be equal to 0;
C: The formula directly shows that, because the direction of N in the formula is perpendicular to the force on the friction surface, and F is parallel to the surface, so C is correct;
D. As long as u and N are not zero, then f must not be zero

Unit 3 of Chinese Book grade 6 Volume 1,