a security guard
安全警卫/保安人员
be under heavy guard
在严密的看管下
The soldier was on guard all night.
士兵整夜站岗。
He struck me while I was off guard.
他趁我不备打了我。
guard against accidents
防止事故
The dog guarded the child day and night.
这只狗日夜守护着那个孩子。
The prisoners were guarded by soldiers.
犯人有士兵看守。