单项选择题
A.butterfly valve
B.spectacle valve
C.check valve
D.globe valve
单项选择题 The tricing pendants should be released().
单项选择题 The total quantity of oil discharge into the sea()for existing tankers 1/15000 of the total quantity of the particular cargo or which the residue formed a part().
单项选择题 The total leg load reactions on an independent leg,self-elevating unit include static and().