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问题 单项选择题

甲容器中有纯酒精13升，乙容器中有水15升，第一次将甲容器中的一部分纯酒精倒入乙容器。使酒精与水混合。第二次将乙容器中的部分混合液倒入甲容器。这样甲容器中纯酒精含量为62.5%，乙容器中纯酒精的含量为40%。那么第二次从乙容器中倒入甲容器的混合液是（）升

A．3

B．4

C．5

D．6

答案

参考答案：C

解析：

乙容器中纯酒精的含量为40%，则第一次由甲容器倒入乙容器的纯酒精为15×40%÷60%=10升。甲容器还有纯酒精13-10=3升；

第二次相当于将100%的甲溶液3升与40%的混合液混合得到62.5%的溶液，采用十字交叉法：

所以第二次从乙容器中倒入甲容器的混合液是5升。

完形填空

任务型阅读（共5小题，每小题2分，计10分）

阅读短文，并按要求完成下列句子。

We know that many animals do not stay in one place．Birds，fish and other animals move from one place to another place at a certain time．They move for different reasons: most of them move to find food more easily，but others move to get away from places that are too crowded．

When cold weather comes，many birds move to warmer places to find food．Some fishes give birth in warm water and move to cold water to feed．The most famous migration is probably the migration of fish，which is called “salmon”（鲑鱼）．This fish is born in fresh water but it travels many miles to salt water．There it spends its life．When it is old，it returns to its birthplace in fresh water．Then it gives birth and dies．In northern Europe，there is a kind of mouse．They leave their mountain homes when they become too crowded．They move down to the low land．Sometimes they move all the way to the seaside，and many of them are killed when they fall into the sea．

Recently，scientists have studied the migration of a kind of lobster(龙虾)．Every year，when the season of the bad weather arrives，the lobsters get into a long line and start to walk across the floor of the ocean．Nobody knows why they do this，and nobody knows where they go．So，sometimes we know why humans and animals move from one place to another place，but at other times we don’t．Maybe living things just like to travel．

小题1:The reason for most of the animals to move is __________________．

小题2:Find the word in the passage which means “ the movement from one place to another of a large group of animals” and write it down here: __________________．

小题3:The underlined word “There” in the second paragraph refers to (指的是) ____________．

小题4:The salmon comes back to its birthplace in order to __________________．

小题5:The lobsters begin to move to another place when __________________．
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多项选择题

电气工作实物交接是指具体实物，如（）等物件要交接清楚。

A.工作票和操作票

B.通知

C.文件

D.仪器仪表

E.工具

F.运行设备
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