Q

Four boys were walking along the street. Two were big and two were small. Although the two in front stop, the two behind could not catch them.
四个孩子沿街走，两小两大分前后；前边孩子虽停步，后边无法抢前头。

A

Carriage wheels.
马车轮子。

点睛一笔

walk along的意思是“向前走，沿着……走”。本题将马车轮子（carriage wheels）拟人化，将四个轮子比喻成四兄弟，不动些脑筋是想不出来的哦！