While flying,a bat makes a sound which hits things and comes back to its ears. In this way it's

题目简介

While flying,a bat makes a sound which hits things and comes back to its ears. In this way it's

题目详情

While flying,a bat makes a sound which hits things and comes back to its ears. In this way it's able to know         the things are and avoid bumping into them.    
[     ]
A. how    
B. where    
C. what    
D. which
题型:单选题难度:中档来源:同步题

答案

B

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