关于手电钻使用说法错误的是（） A.电钻导线要保护好，严禁乱拖，防止轧坏、割破，更不

发布时间：2019-01-26 10:28 │ 来源：www.tikuol.com

题型：单项选择题

问题：

关于手电钻使用说法错误的是（）

A.电钻导线要保护好，严禁乱拖，防止轧坏、割破，更不准把电线拖到油水中，防止油水腐蚀电线；

B.使用时要戴干燥的橡胶手套，穿绝缘皮鞋，潮湿环境工作时，必须站在橡皮垫或干燥的木板上，以防触电；

C.当孔将要钻通时，应适当减轻手臂的压力。卸换钻头时要切断电源，待电钻完全停止转动时方可更换；

D.作业中单手紧握操作手柄缓慢施力，防止意外发生扭伤；

考点：物业维修工物业维修工题库

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Passage Three

Imagine eating everything delicious you want with none of the fat. That would be great, wouldn’t it
New "fake fat" products appeared on store shelves in the United States recently, but not everyone is happy about it. Makers of the products, which contain a compound called olestra, say food manufacturers can now eliminate fat from certain foods. Critics, however, say the new compound can rob the body of essential vitamins and nutrients and also cause unpleasant side effects in some people. So it’s up to consumers to decide whether the new fat-free products taste good enough to keep eating.
Chemists discovered olestra in the late 1960s, when they were searching for a fat that could be digested by infants more easily. Instead of finding the desired fat, the researchers created a fat that can’t be digested at all.
Normally, special chemicals in the intestines (肠道) "grab" molecules of regular fat and break "them down so they can be used by the body. A molecule of regular fat is made up of three molecules of substances called fatty acids.
The fatty acids are absorbed by the intestines and bring with them the essential vitamins A, D, E and K. When fat molecules are present in the intestines with any of those vitamins, the vitamins attach to the molecules and are carried into the bloodstream.
Olestra, which is made from six to eight molecules of fatty acids, is too large for the intestines to absorb. It just slides through the intestines without being broken down. Manufacturers say it’s that ability to slide unchanged through the intestines that makes olestra so valuable as a fit substitute. It provides consumers with the taste of regular fat without any bad effects on the body. But critics say olestra can prevent vitamins A, D, E and K from being absorbed. It can also prevent the absorption of carotenoids (类胡萝卜素), compounds that may reduce the risk of cancer, heart disease, etc.
Manufacturers are adding vitamins A, D, E and K as well as carotenoids to their products now. Even so, some nutritionists are still concerned that people might eat unlimited amounts of food made with the fat substitute without worrying about how many calories they are consuming.

The result of the search for an easily digestible fat turned out to be ______.

A．just as anticipated

B．commercially useless

C．quite unexpected

D．somewhat controversial

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做土的有机质含量试验时，溶液由橙黄色经蓝绿色突变为橙红色时即为终点。( )

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在选择实验室或其他检查时应注意()

A.检查的灵敏度和特异性

B.安全性

C.成本与效果分析

D.检查的时机

E.检查的意义

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薄公英靠什么传播种子（）

A、风力

B、水力

C、电力

D、地心吸引力

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题型：单项选择题

彩色图像在存储，显示，打印有不同方式。常用的彩色模式有（）和（）两种。

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