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问题 单项选择题

嘌呤环中C4来自下列哪种氨基酸？（）

A.甘氨酸

B.天冬氨酸

C.丙氨酸

D.谷氨酸

答案

参考答案：A

写作题

书面表达（10分）根据表格提供的信息，写一篇50字左右介绍你朋友的短文。

My Good Friend

I have a good friend．

                                                                         

                                                                       

                                                                       

                                                                       

                                                                         

                                                                       

                                                                       
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问答题 简答题

冲击危险性检验的方法是什么？
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