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问题 选择题

Rich and famous as he is, he lives in a ________ house in the village. [ ]

A.  modest  

B.  limited

C.  slight  

D.  reserved

答案

答案：A

单项选择题

A group of scientists studying calcium metabolism in laboratory rats discovered that removing the rats’ parathyroid glands resulted in the rats’ having substantially lower than normal levels of calcium in their blood. This discovery led the scientists to hypothesize that the function of the parathyroid gland is to regulate the level of calcium in the blood by raising that level when if falls below the normal range. In a further experiment, the scientists removed not only the parathyroid gland but also the adrenal gland from rats. They made the surprising discovery that the level of calcium in the rats’ blood decreased much less sharply than when the parathyroid gland alone was removed.
Which one of the following, if true, explains the surprising discovery in a way most consistent with the scientists’ hypothesis ？（）

A．The adrenal gland acts to lower the level of calcium in the blood.

B．The adrenal gland and the parathyroid gland play the same role in regulating calcium blood levels.

C．The absence of a parathyroid gland causes the adrenal gland to increase the level of calcium in the blood.

D．If the adrenal gland, and no other gland, of a rat were removed, the rat’s calcium level would remain stable.

E．The only function of the parathyroid gland is to regulate the level of calcium in the blood.
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单项选择题

传染病的基本特征是

A．有病原体、传染性和流行性
B．有传染源、传播途径和易感人群
C．有传染性、流行性和季节性
D．有病原体、易感人群和传播媒介
E．有病原体、传染性、流行性和免疫性
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