清洁卫生间的恭桶时，先应冲水。目的是为了（）
A、冲洗速度快
B、冲去脏物，为下一步清扫做准备
C、节约清洁剂
D、使其畅通
参考答案：B
I really don't know______ I had my money stolen .
A．when was it that
B．that it was when
C．where it was that
D．it was where that
隐性感染的发现主要是通过（）
A.找到病原体
B.发现体征
C.特异性免疫检查
D.病理检查
E.生化检查
