在寒冷的北方，池塘冰面上的空气温度为-10℃，在下述几种情况中，温度恰为0℃的是

能将电压放大10000倍的放大器用电平表示其增益是（）。

A、40dB

B、60dB

C、80dB

D、100dB

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50．If you happen to be the 200th customer to buy Cholesterolblock, you will       .

A．be able to buy it at a low price                         B．be the luckiest one online

C．try it free of charge                                    D．change your diet

51．Liptor®，Zocor®，Crestor® are_______．

A．diseases                B．side effects                   C．medicines         D．cholesterol

52．Where can you most probably read this passage?

A．In a travel guide book．                           B．On a university bulletin board．

C．In a health magazine.                                     D．In a doctor's prescription.

汽油属于哪种有机溶剂（）

A.芳香烃类 

B.醇类 

C.卤代烃类 

D.脂肪开链烃类 

E.脂肪族环烃类

下面哪部书最早用“先生”称呼老师？（）

A.《礼记》

B.《论语》

C.《战国策》

D.《孟子》

在B8018中载频层有几层？（）。

A、1

B、2

C、3

D、4