1、All of them are kids? Why do they have got to keep guard for the kids?
都是小孩子嗎？天使為什么要守著小孩呢？

2、keep guard on the frontiers of the motherland
守衛(wèi)在祖國的邊防線上

3、The policemen keep guard at the airfield and watched every body carefully.
警察們馬上在停機場守候，并且仔細的盯著每一個人。

4、The eldest boy was directed to keep guard at the entrance of the camp.
年紀最大的男生被指派在營地的入口處擔任警戒。