A.開(kāi)啟 B.關(guān)閉 C.半開(kāi)半關(guān) D.四分之一開(kāi)啟
A.45 B.60 C.90 D.12
A.堵漏、預(yù)防 B.預(yù)防、監(jiān)測(cè) C.堵漏、監(jiān)測(cè) D.預(yù)防、堵漏