影响运输成本的基本因素是距离和竞争。()
参考答案:对
吊车吊起10000N的货物以1m/s的速度上升,所用拉力是______N,若以2m/s的速度匀速上升,所用拉力是______N,若以1.5m/s的速度匀速平移,所用拉力是______N.
26. A well-written composition ______ good choice of words and clear organization among other things.
A.calls on
B.calls for
C.calls up
D.calls in