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问题 解答题

一项工程，甲独做需20天完成，乙独做需25天完成．甲的工作效率比乙的工作效率高百分之几？

答案

（

1
20
-
1
25
）÷
1
25
，

=

1
100
÷
1
25
，

=25%；

答：甲的工作效率比乙的工作效率高25%．

改错题

With the popularity of the Internet, more and more people prefer to going shopping online because its advantages. Online shopping can cost us a lot of valuable time. What’s more , there are a wide variety of goods for us to choose from , which may be cheaper than that in shops. Though it is convenience to go shopping online, the problems it caused can’t be ignored. Since we can’t see the actual goods on the Internet, the quality cannot be ensured. Beside, lots of advertisement on the Internet are untrustworthy, so sometimes the customers are easily cheated.

In my opinion, we should be carefully while we are enjoyed the convenience of online shopping.
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单项选择题

完井讨论时应对有井壁取心的井汇报井壁取心的总颗数、收获率、符合率、含油岩心颗数及井深、不含油岩心的颗数、含油岩心的（）及含油气性。

A.电性

B.岩性

C.物性

D.渗透性
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