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举一反三
【单选题】Subways are underground trains, which usually operate 24 hours a day. They are found in larger cities and usually run between the suburbs and the downtown area. Maps and schedules are available from t...
A.
within downtown areas
B.
away from city centers
C.
in or outside big modern cities
D.
between suburbs and city centers
【多选题】下列选项中，可以采用集群液压千斤顶整体提升吊装法的有（ ）。
A.
大型屋盖的吊装
B.
体育场馆钢屋架的整体滑移
C.
油罐的倒装
D.
电厂发电机组的安装
E.
大型电视塔钢桅杆天线整体提升