题目

如果单项式﹣xyb+1与xa﹣2y3是同类项，那么ab=_____． 答案：【答案】9【解析】根据同类项的定义，所含字母相同且相同字母的指数也相同的项是同类项，可得答案．注意同类项与字母的顺序无关，与系数无关．解：由题意，得a﹣2=1，b+1=3，解得a=3，b=2，ab=32=9，故答案为9．She was such a proud person that she would die ____ she would admit she was wrong.A．rather thanB．untilC．afterD．before