1.At midnight he heard a strange sound．半夜里他听到一种奇怪的声音。Light travels much faster than sound．光的传播速度比声音快

相关介绍

1.At midnight he heard a strange sound．半夜里他听到一种奇怪的声音。

Light travels much faster than sound．光的传播速度比声音快得多。

2.The girl has a beautiful voice．那女孩嗓音很美。

They are talking in low voices．他们正小声交谈。