backdrop manhole的意思|示意

美 / / 英 / /

后级沙井；跌级沙井

跌级沙井 ... back inlet gully trap背入集水沟气隔 backdrop manhole后级沙井；跌级沙井 backfill回填；回填土；回填料 ...

后级沙井 ... back inlet gully trap背入集水沟气隔 backdrop manhole后级沙井；跌级沙井 backfill回填；回填土；回填料 ...