Z41H是一种阀门的牌号，其中“z”说明这种阀门是（）
A.截止阀；
B.闸阀；
C.球阀
D.止回阀
参考答案：B
How many ________ has the teacher given you on how to learn English well ?
A．advices
B．pieces of advices
C．advice
D．pieces of advice
The thing __________ we felt very proud is Liaoning aircraft carrier.
A．aboutwhich
B．ofwhich
C．inwhich
D．forwhich
