问题 填空题

四边形ABCD中,对角线AC、BD交于点O,若OA=OC=OB=OD,请你再添加一个条件使四边形ABCD为正方形.填的条件是______.

答案

需要添加的条件是:AB=AD.理由如下:

∵对角线AC、BD交于点O,OA=OB=OC=OD,

∴四边形ABCD是平行四边形,

又∵OA+OC=OD+OB

即AC=BD

∴四边形ABCD是矩形.

又∵AB=AD,

∴矩形ABCD是正方形.

故答案为:AB=AD.

阅读理解

根据短文内容,回答下列问题。

     John was a farmer. He liked to grow flowers in his garden when he was free. One Sunday morning

after breakfast he put on his old clothes and began digging in his garden at eight. He dug and dug. Half an

hour later he suddenly found a coin near his foot. He was very glad, "He put it in his right pocket. A few

minutes later, he found another one. He picked it up and put it in to the same pocket. The same thing

happened for the third,  the fourth and the fifth time."He was very glad and told his wife about it. She was

very glad, too. She said, "A thief took away a lot of coins from a shop a few days ago. The police caught

him but they didn't find any coins." Then John went on digging some more coins, but just when he began

to dig, he felt something cold in his trousers. It ran down one of his legs. He put his hand down quickly

and the coin came into his hand. Now he knew there was a hole in his pocket.

1. What was in John's garden?

                                                                  

2. When did John find a coin in his garden?

                                                                  

3. What did John tell his wife?

                                                                  

4. Where was a hole?

                                                                  

5. How many coins did John dig out in his garden?

                                                                  

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