下载APP
举一反三
【单选题】我国施工项目中常用的安全标志色彩中,红、蓝、黄、绿分别作为
A.
防火色、注意色、警戒色、通行色
B.
防火色、醒目色、注意色、安全色
C.
防火色、警戒色、醒目色、安全色
D.
警戒色、防火色、醒目色、安全色
【单选题】某高压输电线的波阻抗Zc= 380∠- 60°Ω，在终端匹配时始端电压为U1=147kV,终端电压为U2 = 127kV,则传输线的传输效率为（）。
A.
64.4%
B.
74.6%
C.
83.7%
D.
90.2%
【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