Visitors have been asked to keep the woods clean and tidy.请问中间为什么用have been asked

分类: 作业答案 • 2021-12-20 03:03:47

问题描述：

Visitors have been asked to keep the woods clean and tidy.
请问中间为什么用have been asked

答

此处用的是现在完成时的被动语态，故用have been asked
ask 在这里的意思是:要求。

答

have been 表示过去完成时
ask sb. to do sth 是词组,让某人做某事,要求某人做某事
访问者/游客被要求保持森林整洁