30.管線圖中「 5c7dd8e956fae.jpg」代表何種閥?
(A)閘閥
(B)球型閥
(C)蝶形閥
(D)止回閥

答案:登入後查看
統計: A(50), B(923), C(90), D(14), E(0) #1961251