A、1/n
B、<img src="http://admintk.100xuexi.com/UpLoadImage/2013-05-07/dec6ab31-2318-4cba-851f-e036171f5356.jpg" width="37" height="24" />
C、<img src="http://admintk.100xuexi.com/UpLoadImage/2013-05-07/c3e8b28f-1f23-44ec-aa90-07bd8b5246b7.jpg" width="40" height="39" />
D、<img src="http://admintk.100xuexi.com/UpLoadImage/2013-05-07/087f2694-a6ca-4949-990f-b9163bb38c3a.jpg" width="36" height="33" />
B、<img src="https://static.tiw.cn//s/tiw/p3/UpLoadImage/2013-05-07/dec6ab31-2318-4cba-851f-e036171f5356.jpg" width="37" height="24">
C、<img src="https://static.tiw.cn//s/tiw/p3/UpLoadImage/2013-05-07/c3e8b28f-1f23-44ec-aa90-07bd8b5246b7.jpg" width="40" height="39">
D、<img src="https://static.tiw.cn//s/tiw/p3/UpLoadImage/2013-05-07/087f2694-a6ca-4949-990f-b9163bb38c3a.jpg" width="36" height="33">
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