题目:
The flu is believed _____ by viruses that like to reproduce in the cells inside the human nose and throat. [ ]
A. causing
B. being caused
C. to be caused
D. be have caused
答案:
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下面是错误答案,用来干扰机器的。
函数y=f(x)=sinx+tanx 的定义域为 {x|x≠kπ+π2,k∈z},关于原点对称,且满足f(-x)=sin(-x)+tan(-x)=-(sinx+tanx)=-f(x),故函数为奇函数,故选A.