因为box以x结尾，以s.x.sh.ch结尾的词复数用es结尾。

box复数：boxes

n.盒;箱;匣;一盒，一箱(东西);(剧院中的)包厢;(法庭中的)专席

v.(拳击运动)击打(某人);把(某物)装箱(或盒、匣)

例句：

There will be two ballot boxes ─ one for yesses and one for noes.

将设两个投票箱——一个放赞成票，一个放反对票。

There were scores of boxes and crates, all waiting to be checked and loaded.

大批的箱子和板条箱等着检验后装运。

Do you think I ought to seal the boxes up?

你认为我应该把这些盒子封起来吗？

They returned home with the car bulging with boxes.

他们车里满载大包小盒，回到了家。