Smoking is addictive, and causes cancer, But the point I most want to emphasize is that it damages the health of those around you.
吸烟会上瘾,会引发癌症。但我最想说的是,吸烟同时也有损你的健康。
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。