下列反应既属于化合反应,又属于氧化反应的是[ ]
A.氧化汞汞+氧气
B.碳+氧气二氧化碳
C.水氢气+氧气
D.石蜡+氧气二氧化碳+水
答案:B
You’d better not phone the manager between 7 and 8 tomorrow evening; he ________ an important meeting then.
A.will have
B.would have
C.will be having
D.will have had
开式起重机构液压系统用单向节流阀限速为可靠制动常使用()
A.液控单向阀
B.减压阀
C.顺序阀