在喉口部位装有调节机构的文氏管称为调径文氏管，主要用于（）。
参考答案：精除尘
The Greens _____________ a big party on Saturdays. [ ]
A. have
B. had
C. will have
D. has
天然气压缩机停用的注意事项有哪些？
