题目

已知：在△ABC中，AB≠AC，求证：∠B≠∠C．若用反证法来证明这个结论，可以假设（ ） A．∠A=∠B  B．AB=BC     C．∠B=∠C  D．∠A=∠C 答案：C【考点】反证法． 【分析】反证法的步骤中，第一步是假设结论不成立，反面成立，可据此进行判断． 【解答】解：∠B≠∠C的反面是∠B=∠C． 故可以假设∠B=∠C． 故选C． 【点评】本题主要考查了反证法的基本步骤，正确确定∠B≠∠C的反面，是解决本题的关键  通读短文，根据短文内容，在窄格处填入一个使短文内容完整、正确的单词。 Families in different countries are different. Most American families are smaller than the families in other __83__. Most American families have one or two parents and two or more children each. Children in the USA will __84__ their parents when they grow up. They want to find better jobs, so they usually live far away from their parents. They often write to their parents or telephone __85__. And they often go to visit their parents during their holidays. Parents usually let their __86__ choose their own(自己的) jobs. Americans think it is important for young people to decide on their lives by themselves. Today, the families in China are __87__ small. Most Chinese families have one or two parents. But each family can have only one kid, except the twins. When the kids in China grow up, some of them may live far __88__ their parents because they want to find good jobs, some of them may live with their parents __89__ they don't want to make their parents feel lonely(孤独的) . Some of the parents in China don't let their children choose their own jobs. They choose the jobs for their kids. Most of them think they can give their kids a __90__ future. It's not good for young people