题目内容：

In this way it is able to know ----the things are and avoid bumping into them.
While flying ,a bat makes a sound which hits things and comes back to its ears .

优质解答

是要翻译吧?
“就是靠这种方法,（蝙蝠）知道前方是什么东西并且避免撞上他们.”
“在飞行的时候,蝙蝠发出一种声波；这种声波打到前方物体上并反弹至蝙蝠耳中.”