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问题 单项选择题

4位烯νC=C

A．3500cm-1
B．2970cm-1
C．1700cm-1
D．1615cm-1
E．870cm-1
黄体酮的红外吸收光谱中，以下吸收峰的波数是

答案

参考答案：D

选择题

If I got married in the UK I _____ a present, but is I got married in Italy, I would have to give a present.

A．will expect

B．were to expect

C．had expected

D．would expect
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单项选择题

理想的牙刷刷毛应具有的特点是

A．易吸水变软

B．刷毛端有孔

C．具有适当弹性

D．防霉

E．直径与长度成比例
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