题目内容：

be sure+从句/be sure to do sth /be sure of sth/doing sth 有什么区别吗?

优质解答

都一样.
由于是从句,所以后面可以接足够长的句子或者有足够的句式变化,语气上平和,正式.
I'm sure that he came to school early.
而sure of doing 就是简单表达“我确定干什么”.
I'm sure of coming to school early.