罩式退火炉内罩一般用（）制成。
A.耐热纤维
B.耐热钢板
C.轻质耐火材料
D.塑料板
参考答案：B
The real-name policy for train tickets has been applied to all trains since January 1,2012 in China, ______ I think will make it easy for people to get tickets.
A．which
B．when
C．what
D．where
将下表中的Y物质加入或通入X物质中，在反应所得溶液中一定只含一种溶质的是
