A、<img width="63" height="28" src="http://img.wangxiao.cn/examfiles/imgcache/attached/image/20140605/20140605151357_2205.png" />
B、<img width="63" height="28" src="http://img.wangxiao.cn/examfiles/imgcache/attached/image/20140605/20140605151406_5356.png" />
C、exdx
D、exIn xdx
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