A.無(wú)開(kāi)關(guān)要求B.關(guān)閉C.半開(kāi)啟D.全開(kāi)啟
A.一個(gè) B.二個(gè) C.三個(gè) D.四個(gè)
A.30s B.35s C.40s D.45s