题目

计算： （1） （2） 答案：解：原式=3 2 -3-2 2 -1= 2 -4 解：原式=-2+3+ 3 +1- 3 =2Mr. Black is very happy because the clothes made in his factory have never been 　　　. A. popular　　　 B. more popular　　　 C. most popular　 D. the most popular