题目

3a2﹣6ab﹣5b5﹣2a4b2+a3b按字母a降幂排列． 答案：【1】﹣2a4b2+a3b+3a2﹣6ab﹣5b5 She’s already an hour late, What _____to her? A can have happened       B may happen C should have happened       D may have happened