使蛋白质分子在280nm具有光吸收的最主要成分是（） A.丝氨酸的_爱下问搜题

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问题单项选择题 A1/A2型题

使蛋白质分子在280nm具有光吸收的最主要成分是（）

A.丝氨酸的羟基

B.半胱氨酸的巯基

C.苯丙氨酸的苯环

D.色氨酸的吲哚环

E.组氨酸的咪唑环

答案

参考答案：D

选择题

Excuse me, Marcia, a reporter from Vanity Fair ____ all day. Could you speak to her now?

A. phones
B. has phoned
C. has been phoning
D. phoned

选择题

—Would you like some juice or coffee?

—_____I really don't mind. [ ]

A. Either

B. Neither

C.Both