北半球大部分地区正午太阳升得最高，白昼时间最长，黑夜时间最短的一天是在（  ）

已知： $f\left(x\right)=\left\{\begin{array}{c}{2}^{x-2},x\le 2\\ {\log }_2(x-1),x>2\end{array}\right.$则f(f(5))等于(   )

如图所示，直线a∥b，∠1=35°，∠2=90°，则∠3的度数为（   ）

完形填空
    If you often have a cold, headache or backache, there is something wrong with your health. Eating healthy food 1good for our health.
    Tofu（豆腐）, milk, vegetables are healthy for us. Tofu is a kind of traditional（传统的）2food. We often 3 it in China. Now more and more people 4 other countries think tofu is good for health, 5. They also like eating it. Milk is 6  kind of health food. Every day you should  7  one or two glasses of milk.
    It can 8 us strong.
    Vegetables are very important. You should 9 them. There are vitamin(维他命) A, B, C, D , E and so on in them.
    As we know, it's important10 a balanced diet(均衡饮食). We must have the right kinds of food. We should also eat some pork, chicken and beef. We should eat more fruit and vegetables but less meat.

教室里有54张课桌，要摆6行，平均每行摆____张．