“己所不欲，勿施于人”的实质是（    ）

设为正整数，若和除以的余数相同，则称和对同余，记作.已知，，则的值可以是( ▲ )

看图写数。

       ____                  ____                  ____                    ____ 

质量为m的探月航天器在接近月球表面的轨道上飞行，其运动视为匀速圆周运动．已知月球质量为M，月球半径为R，月球表面重力加速度为g，引力常量为G，不考虑月球自转的影响，则航天器的（     ）

根据短文内容, 回答下列问题。
    I am Helen. I study in the No.1 Middle School now. There are forty-five students in my class. All of the students like to travel(旅游). Eight students like to travel by plane, because they think it is fast. It only takes about two hours to travel by plane from Beijing to Shanghai. But some students think taking a plane is too expensive. Twenty-two students usually travel by train. The trains are very fast, but they are cheaper (更便宜). And they can see interesting things through the windows. Fifteen students love to travel by car. Their parents drive them to some beautiful places. They can have a good time with the family. Do you know how I like to travel? I'm one of the twenty-two students.