如果向北走20米记为是+20米,那么向南走70米记为( )米.
﹣70
旋转阳极X线管定子的极数一般是
A.5
B.4
C.3
D.2
E.1
You can ______ this car with that one; then you will see which one is better.
A.match
B.share
C.compare
D.measure