keep guard造句

1、All of them are kids? Why do they have got to keep guard for the kids?
都是小孩子吗？天使为什么要守着小孩呢？

2、keep guard on the frontiers of the motherland
守卫在祖国的边防线上

3、The policemen keep guard at the airfield and watched every body carefully.
警察们马上在停机场守候，并且仔细的盯着每一个人。

4、The eldest boy was directed to keep guard at the entrance of the camp.
年纪最大的男生被指派在营地的入口处担任警戒。