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问题 单项选择题

压缩机曲轴经（）直接与防爆电机相连，由电机直接驱动，它接受电机扭矩形式输入的动力，并把它变为活塞的往复作用力压缩气体而做功。

A.十字头

B.连杆

C.飞轮

D.活塞杆

答案

参考答案：C

单项选择题

属于泊松分布的控制图为（）。

A．

B．Me—R图

C．p图

D．c图
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单项选择题

Scientists have rediscovered certain food crops, once commonly cultivated in the New World, which contain more protein per pound than do current staple food crops such as rice and wheat. Scientists claim that cultivation of these crops could greatly benefit densely populated countries that have low per-person calorie intake and inadequate source of protein.
Which of the following, if true, casts the most serious doubt on the claim made above

A．The average yield per acre of the rediscovered crops is substantially less than that of the current staple food crops.

B．Many important food crops, such as tomato, originated in the New World.

C．Wheat yields more protein per pound than does rice.

D．The rediscovered crops have more caloric per pound than do current, staple food crops.

E．(E) As few as 20 different food crops provide the bulk of the planet’s food supply.
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