问题 填空题

已知命题“线段垂直平分线上的任意一点到这条线段两个端点的距离相等”,用“如果… ,那么…”的形式写出它的逆命题,并判断其真假.

逆命题:                                                                       .

这个逆命题是      命题(填“真”或“假”).

答案

如果一个点到线段的两端点的距离相等,那么这个点在线段的垂直平分线上. 真

任何一个命题都是由条件和结论两部分组成,原命题的条件:点在线段的垂直平分线上,结论:点到这条线段的两端点的距离相等;逆命题是把原命题的条件和结论对调。逆命题:如果一个点到线段的两端点的距离相等,那么这个点在线段的垂直平分线上。根据定理“到线段的两端点的距离相等的点在线段的垂直平分线上”知道逆命题是真命题。

完形填空

阅读下面对话,掌握其大意,并根据所给字母的提示,在标有题号的右边横线上写出一个英语单词的完整、正确形式,使对话通顺。

J =" John      " R = Robert

J:  I hear that an important meeting is to be ( 76 ) h       in our    76.           

city. What’s it about?

R:  It’s said that its (77) g       is to make clean drinking         77.         

water available to all.

J:   Who do you know will (78) t        part in the meeting?      78.       

R:   Representatives from more than 80 countries, as is

(79) r       on TV.                                        79.      

J:   Could you tell me (80) m       ?                         80.        

R:   Sure! Three things will be (81) d         at the meeting       81.        

—ways of making good use of water, (82) r       water      82.         

pollution and saving water.

J:   That’s good news for people in this area. As you may know,

there are too (83) m       factories around here, which let     83.        

out plenty of poisonous gas and polluted water. So we eagerly

hope that strong (84) m        will be taken to stop the        84.       

water pollution.

R:   I quite agree with you. Let’s hope for the day to come as

soon as (85) p        .                                 85.        

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