How to write? Composition! Urgent! In the picture, there are: audience (old people, children, adults in suits, dogs), goalkeeper, players, field: schoolbag, green grass. This is a small football match, to write a tense atmosphere. Thank you!

Wonderful football match in a corner of the school playground, there is a piece of green grass, where the children often regard as their happy football field. Look, these children are coming again, they are going to hold a wonderful football match here! They will start the warm-up before the game. Look, how many smiles the players have

Composition of exercise 6 in Volume 2 of grade 6 of primary school

Dear cousin
Open the picture album of memory, I still remember the scene we played together three years ago. Although the past is vivid, but three years later, I have no chance to go back to visit you. How are you? The schoolwork of grade three is very heavy. You should pay more attention to your health
I'm in grade six this year, and I have 20 days to take the exam. I'm about to face the first turning point in my life. My heart is like overturning a Chinese gourmet bottle, savoring the ups and downs. I finally know your mood three years ago. Everyone is always worried before the exam, and I'm not exception. I always worry that I'll fail the exam, which will not only affect my study in middle school in the future, Every time I think about it, I feel like I'm carrying a heavy burden, which makes me gasp. Therefore, I try my best to review the knowledge I've learned for six years now. I dare not be distracted in class. I listen carefully. My brain keeps running normally and my nerves are tight. As a result, I can't support it any longer, Later, my neighbor's sister told me that she had to read all kinds of books when she was reviewing. Finally, when she was doing her homework, she found that there were still many places that she didn't master well, and many places didn't focus on reviewing. So she made a scientific schedule for herself, Do everything in strict accordance with the schedule in the daily schedule, so work and rest should be combined to do everything in an orderly way. I don't know if you agree with this method. If you have more effective methods, please write back to me
Although every day in the tense preparation, but I still can't help looking forward to junior high school life. Junior high school homework burden is very heavy, every day more than ten homework, and after all, it is a new environment, I must strive to adapt, can't play, to consolidate the basic knowledge, for the future study to lay a good foundation
Well, a thousand words, I can only congratulate you on entering the school you are satisfied with. Work hard for our dream. I will visit you in the summer vacation. You must pay attention to your health!
Your cousin: so and so
June 4, 2005

How to prove the necessary and sufficient condition of vector collinearity B = γ a (a is a non-zero vector)?

Adequacy:
If B = ya, then ya-b = 0, that is to say, there are two numbers that are not all 0: K1 = y, K2 = - 1, such that the linear combination of a and B K1 * a + K2 * b = 0, which is the definition of linear correlation! So a and B are linearly correlated. (collinear)
necessity:
If a and B are collinear, that is, linearly correlated, then there are two numbers K1 and K2 that are not all zero, such that K1 * a + K2 * b = 0. We can deduce that K2 must not be 0. (because if K2 = 0, then K1 * a = 0, and a is a non-zero vector, then K1 = 0 must exist, which is contradictory to "K1, K2 are not all zero")
So both sides of the equation can be divided by the nonzero number K2:
b=-(k1/k2)*a
Y = - (K1 / K2)
B = ya

Two examples of force balance
Supporting force and pressure are balance force, electric lamp has pull force and gravity
I'm talking about what force and what force is balance force

In equilibrium
Support force and pressure are not equilibrium force! Because the force is not acting on the same object
Support and gravity are balance forces!
Attention! Gravity ≠ pressure---------------

Find the unknown 2 / 5x-4.8 * 2 = 0.4

2/5x-4.8*2=0.4
0.4x-9.6=0.4
0.4x=9.6+0.4
0.4x=10
x=10/0.4
x=25

XY / (100-x) = 3 / 20, how to solve 2XY / (100-2x = 2 / 5?

Xy = 3 / 20 (100-x);
From the two formulas, xy = 1 / 5 (100-2x);
That is to say, 3 / 20 (100-x) = 1 / 5 (100-2x) gives x = 20
Substituting x = 20 into the solution, we get y = 0.6

The use of abacus

Abacus is rectangular, surrounded by wooden frame, inside fixed with a small stick, wooden beads on the stick, the middle of a beam and abacus is divided into two parts, each stick's upper half has two beads, each bead when five, the lower half has five beads, each bead on behalf of one

101 * 0.78-0.91 * 78

101*0.78-0.91*78
=1.01*78-0.91*78
=(1.01-0.91)*78
=0.1*78
=7.8

Let Sn = (1 / 2 + 1 / 3) + (1 / 2 ^ 2 + 1 / 3 ^ 2) +.. + (1 / 2 ^ n + 1 / 3 ^ n), LIM (n - > ∞) Sn =?

Sn=(1/2+1/3)+(1/2^2+1/3^2)+..+(1/2^n+1/3^n)
=(1/2+1/2^2+...+1/2^n)+(1/3+1/3^2+...+1/3^n)
=1-1/2^n+(1-1/3^n)/2
=1+1/2-1/2^n/1/(2*3^n)
So LIM (n →∞) Sn = 1 + 1 / 2-0-0 = 1.5

Verification: √ (a ^ 2 + 1 / b ^ 2 + A ^ 2 / (AB + 1) ^ 2) = {a + 1 / B-A / (AB + 1)} {} absolute value
Verification: √ (a ^ 2 + 1 / b ^ 2 + A ^ 2 / (AB + 1) ^ 2) = {a + 1 / B-A / (AB + 1)} {} absolute value
Calculation: √ (1 + 2005 ^ 2 + 2005 ^ 2 / 2006 ^ 2) - 1 / 2006
Speed, online, etc

How to write? Composition! Urgent! In the picture, there are: audience (old people, children, adults in suits, dogs), goalkeeper, players, field: schoolbag, green grass. This is a small football match, to write a tense atmosphere. Thank you!