速度的方向：质点在某一点的速度方向，沿曲线在这一点的______．
曲线运动某点的速度方向沿曲线上该点的切线方向．
故答案为：切线方向．
计算（2a+b）（2a﹣b）的结果是[ ]
A．4a2﹣b2
B．b2﹣4a2
C．2a2﹣b2
D．b2﹣2a2
His suggestion that much attention ______ wildlife is worth ______. [ ]
A. be paid to protect, being considered
B. be paid to protecting, considering
C. should be paid for protecting, to consider
D. should be paid on protecting, to consider
