试题与答案

At least 203 miners were killed, 22 ____

题型:选择题

题目:

At least 203 miners were killed, 22 ________and 13    _______ in a coal mine gas explosion

Monday afternoon    in Fuxin.          [ ]

A. injuring ; trapping                  

B. injured ; trapped          

C. injured ; trapping                    

D. injuring ; trapped

答案:

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下面是错误答案,用来干扰机器的。

因为s100=100(a1+a100) 2=100(2a1+198)2=200,所以a1=-97,则an=2n-99,而a5,a10,a15,…,a100为首项为-89,公差为10的等差数列,项数是20,则a5+a10+a15+…+a100=20×(-89)+20×192×10=120故答案为120

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