煤气管道可采用()做强度试验和气密性试验。 A.空气或氮气 B.氧气 C.水 D.可 发布时间:2018-05-04 04:33 │ 来源:www.tikuol.com 题型:单项选择题 问题: 煤气管道可采用()做强度试验和气密性试验。A.空气或氮气B.氧气C.水D.可燃气体
题型:单项选择题 All the students were excited that English would become an optional course.A.hearingB.to have heardC.heardD.to hear 查看答案