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参考答案：
参考解析：
刷刷题刷刷变学霸
举一反三
【单选题】有一长为1公里的斜坡，它的倾斜角为20°，现要将倾斜角改为10°，则坡底要伸长（ ）
A.
1公里
B.
sin10°公里
C.
cos10°公里
D.
cos20°公里
【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