单项选择题
Though the topics in small talk are not important, smal...
判断题Though the topics in small talk are not important, small talk itself is very important.
在给水排水的施工安装工程中,常用的材料主要有管材、附件、( )及辅助材料。A.阀门B.截止阀C.蝶阀D.止回阀
单项选择题在给水排水的施工安装工程中,常用的材料主要有管材、附件、( )及辅助材料。
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