偏光镜的用途有（）
A.测折光率
B.测光性
C.测多色性
D.测双折率
参考答案：B, C
煤矿井下电气管理必须做到三全是指防护装置全、（），图纸资料全。
Liu Qian, a magician for Taiwan, ______ audience of thousands on the 2009 CCTV Spring Festival Show.
A．appealed to
B．applied for
C．approved of
D．appointed with
