(1/2-1/3)+(1/3-1/4)+(1/4-1/5)
A.1/10
B.1/5
C.3/10
D.2/5
参考答案:C
机车在并联运行中,出现电网电压小于()伏时,应转换为低电压级运行。
A.1500
B.1100
C.1000
D.800
Table tennis is easy to learn, and, by the same token , boys don''t need a lot of space to practice it.
A.by the same rule
B.symbolically
C.moreover
D.by logic