A:get; across
B:get; over
C:give; away
D:give; out
平面上4条直线相交,交点的个数是( )
某质点在恒力F作用下从A点沿图4所示曲线运动到B点,到达B点后,质点受到的力大小不变,但方向恰与F相反,则它从B点开始的运动轨迹可能是图中的哪条曲线 ( )
I haven't seen _______ this since I began to collect stamps.