下载APP
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
【单选题】调节系统的工程整定，其目标一般为（）
A.
调节过程具有较小的衰减比，超调量要小，调节时间越短越好，又要没有余差
B.
调节过程具有较小的衰减比，超调量要大，调节时间越长越好，又要没有余差
C.
调节过程具有较大的衰减比，超调量要大，调节时间越短越好，又要没有余差
D.
调节过程具有较大的衰减比，超调量要小，调节时间越短越好，又要没有余差