【单选题】Two long parallel wires are placed side - by - side on a horizontal table. If the wires carry current in opposite directions,
A.
both wires are lifted slightly
B.
both wires are forced against the table's surface
C.
the wires attract each other
D.
the wires repel each other
【单选题】If two ACgenerators are operated in parallel, the load is distributed evenly by .
C.
changing field excitation
D.
adjusting the governor settings
【简答题】四百万八千零九十写作______,四舍五入到万位是______万.
【单选题】隧道断面面积应满足旅客()要求,衬砌、洞门结构、洞口仰坡、轨下基础应安全稳定,并具备良好的防排水系统。
【单选题】隧道断面面积应满足旅客( )要求,衬砌、洞门结构、洞口仰坡、轨下基础应安全稳定,并具备良好的防排水系统。
【简答题】三千六百万零七十写作______,四舍五入到万位,约是______万.
【简答题】三亿零五百万六千写作______,把它四舍五入到亿位记作______亿.
【简答题】四十二亿六千八百万写作______,四舍五入到亿位是______.