Is there a problem with the topic, such as the question, is there a problem with the topic? Or do I

There is an error in the question, the pyramid is a category, because it contains a triangular pyramid, a quadrangular pyramid, etc., it cannot be said how many faces, the answer explains that it is a cone composed of a surface and a circle.

Summary. There may be the following situations without questions: 1. If you brush less, try to brush more, and there may be questions; 2. The field itself has many answers, and there are few questions; 3. If it is a new respondent, brush more brushes, raise the number, about a week; 4. If it is an old answerer, it may be because the quality is not good, etc., it is necessary to improve the quality of the answer5. If it is a day to brush a little question, and then there is no question, the next day is the same situation, this is the low quality is limited, improve it; 6. If you haven't brushed the questions for a period of time, you will be considered inactive by the platform, resulting in not pushing the questions, and brushing them for a week; 7. If you keep refreshing the question bank and brushing out the questions, but don't do the questions (just referring to the situation that you can brush out a lot of questions, but don't grab them), you will also be restricted, and you will insist on refreshing them for a week.

Kiss, it may be that the quality of your answers is too low

I'm still a little confused, can you be more detailed?

There may be the following situations if there is no topic: 1. If you brush less, try to brush more, and you may have a question; 2. The field itself has many answers, and there are few questions; 3. If it is a new respondent, brush more brushes, raise the number, about a week; 4. If it is an old answerer, it may be because the quality is not good, etc., it is restricted to brush the question, and then it is necessary to improve the quality of the answer 5. If it is a day to brush a little question, and then there is no question, the next day is the same situation, this is the low quality is restricted, and it is good to improve it; 6. If you haven't brushed the questions for a period of time, you will be considered inactive by the platform, resulting in not pushing the questions, and brushing them for a week; 7. If you keep refreshing the question bank and brushing out the questions, but don't do the questions (just referring to the situation that you can brush out a lot of questions, but don't grab them), you will also be restricted, and you will insist on refreshing them for a week.

The title refers to the meter, that is, the stone falls from a height of meters above the ground and is photographed by the camera with a trail that starts at about 54 centimeters from the ground and ends at a distance of about 42 centimeters from the ground. The time it takes for a stone to fall from the beginning of the trail to the end of the trail, that is, the time of the camera. So there is the following calculation:

Time from the stone to the beginning of the trail t1=[(2 h1) g] seconds Time from the stone to the end of the trail t2=[(2 h2) g] seconds The time of the camera = t2-t1=s.

You don't actually need to look at the left picture, just look at the right picture. The title has already told you where the stones are falling. Just look at the figure on the right to calculate.

D is not right, and after the derivative, it is not E 2.

A is greater than 0 and a is not equal to 1

f（x）＝f（x）－g（x）= log a (x+1) -log a (1-x) =log a [(1+x)/(1-x)]

Zero and negative numbers have no logarithm: x+1 0, 1-x 0, define the domain -1 x 1f(-x) =log a [(1-x) (1+x)] log a [(1+x) (1-x)] f(x), odd function.

f(x)+f(y)=log a [(1+x)/(1-x)] log a [(1+y)/(1-y)]

log alog a [(1+x+y+xy) (1-x-y+xy)]f[(x+y) (1 xy)]=log alog a [(1+x+y+xy) (1-x-y+xy)]f(x)+f(y)=f(x+y).

The sum of the odd number is an odd number, and it can't be 30 (even), which is the law of junior high school.

No problem, the brain will not be old, and the 9 will be reversed as "6".

The normal situation is unsolvable, how can the result of the addition of 3 odd numbers be even? But since it's a brain teaser, you can try an abnormal solution, such as turning 9 upside down into 6