sure不是。sure只能当形容词和副词。
sureadj.确信；确知；肯定；有把握；adv.(表示同意)当然；(加强语气)确实
I\'m sure you\'ll grow to like her in time.
我肯定你慢慢就会喜欢她了。
Make sure that sign\'s the right way up.
一定不要把这招牌挂颠倒了。
Your work is all right but I\'m sure you could do better.
你的工作还算可以，但我相信你可以干得更好。
