what can i do to make her smile ,what i can do to make her s

第一句 What can i do to make her smile ? 这是一个正确的疑问句.
what i can do to make her smile 这句不适合单独使用,而是适合充当一个从句,比如说当一个宾语从句就很合适： I don't know what i can to to mak her smile.