1. Everyone knows that if he shouts in the vicinity of a wall or a mountainside, an echo will come back.
    大家都知道，在墙壁或山腰附近发出的喊声，就会听到回声。

2. It is now possible not only to locate a shoal but to tell if it is herring, cod, or other well-known fish, by the pattern of its echo.
    不仅能够确定鱼群的位置，而且可以根据鱼群回声的特点分辨出是鲱鱼、鳕鱼，这是人们所熟悉的其他鱼。

3. This echo-location in bats is often compared with radar,the principle of which is similar.
    蝙蝠的回声定位常常可与雷达比较,其原理是一样的.

4. The echo was sent from the cave.
    回声是从洞里传出的.

5. The return of the echo will elapse longer time.
    回声返回所耗的时间越长了.

6. This echo-location in bats is often compared with radar, the principle of which is similar.
    人们常把蝙蝠的这种回声定位与雷达相比较, 因为它们的原理是相似的.

7. The further off this solid obstruction, the longer time will elapse for the return of the echo.
    固体障碍物越远。回声返回所用时间就越长。

8. This echo-location in bats is often compared with radar, the principle of which is similar.
    蝙蝠这种回声定位常常可与雷达相比较，其原理是相似的。

9. And we have only to turn to that extraordinary discovery of echo-location in bats to see a case in which the voice plays a strictly utilitarian role.
    我们只要看一看蝙蝠回声定位这一极不寻常的发现，就可以探究一下声音在什么情况下有绝对的实用价值。

10. So was born the echo-sounding apparatus, now in general use in ships.
    这样就产生了目前各种船舶上普遍应用的回声探测仪。