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问题 选择题

下列反应中，属于加成反应的是

A．CH4+C12CH3Cl+HCl

B．CH2= CH2+ C12

C．+Br2+HBr

D．CH4+2O2CO2+2H2O

答案

答案：B

有机物分子中双键或三键两端的碳原子与其他原子或原子团直接结合生成新的化合物的反应叫加成反应，所以B正确。AC都是取代反应，D是氧化反应，答案选B。

问答题

In October 2008 Ronger Properties Joint Stock Co successfully issued corporate bonds of RMB 12 million yuan for three years. By the end of 2010 the net assets of Ronger Properties Joint Stock Co were RMB 80 million yuan. During the past two years it has been able to repay the interests due for the corporate bonds.In order to expand its business, the board of directors of Ronger Properties Joint Stock Co adopted a resolution intending to issue another set of corporate bonds to the public investors.Required:Answer the following questions in accordance with the relevant provisions of the Securities Law of China, and give your reasons for your answer:

(c) State the statutory period of underwriting for the proposed issuance. (1 mark)
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单项选择题

DNA上的外显子(exon)是

A．不被转录的序列

B．被转录，但不被翻译的序列

C．被转录也被翻译的序列

D．调节基因序列

E．以上都不对
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