试题与答案

含不同羟基的黄酮类化合物的酸性强弱顺序为()。 A.7,4′-二羟基>7-羟基>5-

题型:单项选择题

题目:

含不同羟基的黄酮类化合物的酸性强弱顺序为()。

A.7,4′-二羟基>7-羟基>5-羟基>一般酚羟基

B.7,4′-二羟基>一般酚羟基>5-羟基>7-羟基

C.7,4′-二羟基>4′-羟基>一般酚羟基>5-羟基

D.7,4′-二羟基>5-羟基>7-羟基>一般酚羟基

E.一般酚羟基>7-羟基>5-羟基>7,4′-二羟基

答案:

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Every tourist must visit Greece at least once in life. This country is really a vacation heaven. It is the perfect blend of history and art with adventure and romance. You can dive into deep blue waters, climb up the mountains or enjoy ancient architecture and history.

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Athens, the capital of Greece, has three bus terminals. Buses to different part of Greece leave from different terminals.

Air-conditioned express buses(空调快车) also operated between major cities. They are faster and more comfortable than other buses. Tourists can choose guided Greece bus tour. These tours are the perfect way of exploring this great country.

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A.to different cities in Greece

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