外圆车刀车件老响:帮我解释一下

来源:百度文库 编辑:神马品牌网 时间:2024/05/03 04:44:37
when people have to be at their place of work?
其中的have to be 在语法中怎么解释?
为什么要加be?

be是系动词,后接介词短语作表语, eg. He is at home./ He has to be at home.