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【单选题】
有关人体的组成元素的说法中错误的是（ ）A.
组成人体自身的元素约有50多种
B.
人体内的碳、氢、氧、氮四种元素主要以水、糖类、油脂、蛋白质和维生素形式存在
C.
人体内含量较多的元素有11种
D.
由于微量元素的含量非常少，因此，对人体健康的影响也很小
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反馈参考答案：
举一反三
【单选题】In a two-stroke engine the camshaft rotates at____ the engine rotational speed.
A.
half
B.
twice
C.
the same speed as
D.
four times
【单选题】Each cylinder in a two stroke cycle engine experiences combustion（）.
A.
once each crankshaft revolution
B.
twice each crankshaft revolution
C.
every other crankshaft revolution
D.
every fourth stroke
【简答题】如何检测点火控制器？
【单选题】My grandfather is such a forgetful person that he has to _______ many things, even his daily meals. [ ]
A.
be remembered by
B.
be reminded of
C.
be memorized
D.
be reminded
【单选题】In two-stroke engine the crankshaft is connected with ____ by means of the connecting rod.
A.
the stuffing box
B.
the piston
C.
the crosshead
D.
guide plate
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