双绞线将二根绝缘导体相互扭绞的目的是()
A.提高传输速度
B.减少电磁干扰
C.增大抗拉强度
D.增大传输距离
参考答案:B
---What you when it is snowing?
--- I do some washing with my mother at home.
A.are, do
B.are, doing
C.do, do
D.are, going to do
I don’t know________.
Because he has to look after his mother.
A.why he is leaving
B.why is he leaving
C.whether he is leaving
D.whether is he leaving