题目

观察下图，寻找对顶角：(1)如图1，图中共有 对对顶角(2)如图2，图中共有 对对顶角(3)如图3，图中共有 对对顶角(4)若有n条直线相交于一点，则可形成多少对对顶角？ 答案：【答案】2 6 12 n(n－1) 【解析】（1）根据对顶角的定义计算即可得解；（2）根据对顶角的定义计算即可得解；（3）根据对顶角的定义计算即可得解；（4）根据对顶角的对数和直线的条数的规律写出即可；（1）有2对对顶角；（2）有6对对顶角；（3）有12对对顶角；（4）有n条直线时，有n（n−1）对对顶单词拼写（共10小题；每小题1分，满分 10分） 根据下列句子及汉语注释，在答题卡相应的位置写出空缺处各单词的正确形式。（每空只写一词） ______________(包围) by the police, the thief had no choice but to surrender(投降). There are seven ____________(大洲) in the world. He is a man full of ________________(冒险). I lose __________(耐心) with my family. The ship sank in the __________(猛烈的，激烈的)storm. It’s ______________(有害的) to your eyes to read in the bus. If you want to get the job, you should make an __________ (印象)on the interviewers. It’s bad ___________(礼貌) to interrupt. It was not our __________(错) that we were late. I’d like to ___________(确认) my flight.