be sure to do的主语是人还是it?

be sure to do的主语是人还是it? be intended to do 主语是人还是物,还有intend to do 和 be intended to do be sure of be sure to do 的区别· 祈使句时 是to be sure 还是 be sure make sure,be sure of ,be sure to do,for sure的区别 be sure to do的意思 sure的用法be sure of doing和 be sure to do有什么区别呀? it作形式主语的问题it 作形式主语的句型是 it + be动词,还是it + 谓语动词? It must be terrible to be grown up!这是形式主语,真正的主语to be grown u 用Be sure to、Be sure to do 、Be sure of、Be sure that 造句 形式主语 it should be avoided to do sth. be sure toI am sure the 3.4 to 4 oz will be fine.请问是要3.4的还是4