可以度量(60米),有两个端点(起点,终点),在直跑道上,所以画出的是一条线段;
故选B.
Mr. Wang was very poor, _____ he was very happy. [ ]
A. and
B. but
C. or
D. so
体操运动员在上单杠之前总要在手上涂些镁粉,是通过______的方法来增大摩擦;而在杠上做回环动作时,手握杠又不能太紧,这是通过______的方法来______摩擦.