题目

 I’m going to ________ time with my grandparents this vacation.    A. spend   B. take   C. cost   D. pay 答案：A把多项式a4+4a3b-6ab2+4ab3按b的降幂排列为4ab3-6ab2+4a3b+a44ab3-6ab2+4a3b+a4．