气开式调节阀是一种有气关、无气则开的调节阀。
参考答案：错
解析：气开式调节阀是一种有气开、无气则关的调节阀。
―Do you know _____the Capital Museum?
―Next Friday.
A. when will they visit
B. when they will visit
C. when did they visit
D. when they visited
牙石
