One behind another.

一前一后地。

Of seats on a bicycle or of horses, arranged one behind another.

前后排列的(如脚踏车上之座位或一前一后而非并驾之两马)。

A pair of horses harnessed one before the other.

一前一后之两马。

A bicycle for two or more, with seats placed one before the other.

座位一前一后之脚踏车；协力车。