题目：
其他题
Write down the numbers of the topic sentences in the following passages.
（1）When you throw a ball up into the air as fast as you can, the ball reaches a point where it seems to pause for a moment, and then it comes down. （2）When a bullet (子弹) is shot straight up, it will travel much faster and higher than a ball, but it, too, will come down. （3）Whatever goes up must come down.（4） We have always thought this to be true.（5） An airplane may climb to a height of seventeen miles and then travel far and long. （6）Yet it does not stay up forever.（7）Finally, like every-thing else, the plane must come down.
答案：
<查看本题扣1积分>