题目

如果a=b，那么下列结论中不一定成立的是（ ） A . =1 B . a﹣b=0 C . 2a=a+b D . a2=ab 答案：AThanksgiving in the United States is _____ the fourth Thursday ______ November.A. on; on B. on; to C. on; in D. in; in