【单选题】Vapor or fumes may ________ on piping, duct, or stack walls.
【单选题】“口腔生殖综合征”患者应及时补充( )。
【单选题】Vapor of fumes may on piping , ducts, or stack walls.
【单选题】Vapor or fumes may_______ on piping, ducts, or stack walls. ( )
【单选题】Vapor of fumes may ______ on piping, ducts, or stack walls.