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问题 选择题
复数
1-i
1+i
的模为（　　）
A．0B．1C．2D．
2
答案

1-i
1+i
=
(1-i)(1-i)
(1+i)(1-i)
=
-2i
2
=-i，故复数
1-i
1+i
的模等于1．

故选B．

问答题

如何评价秦始皇？

                                                                                                                                                            

                                                                                                                                                            

                                                                                                                                                            

                                                                                                                                                            

                                                                                                                                                            

                                                                                                                                                            

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单项选择题

航煤精制的对象主要是（），尤其是硫醇。硫醇不仅有恶臭，而且使油品安定性变坏，且具有腐蚀性。

A、烯烃

B、芳烃

C、氧化物

D、硫化物
查看答案