be sure of sth 对某事很确定
I am sure of his guilt.我确定他有罪.I am sure of his coming.我确定他会来.
be sure to do sth 一定会做某事
I am sure to close the window after school.放学后我一定会关窗的.
I am sure to help you tomorrow.我明天一定会帮你.
be sure that 对某事很确定 后面加句子
I am sure that he will achieve his goal.我确定他会实现目标的.
He is sure that his mother will come to see him this afternoon.他确信他妈妈今下午会来看他.