leap
关于leap和jump的不同，下面几点该注意：
（1）leap不及jump普通，但Look before you leap和a leap in the dark和by leaps and bounds各种表达方式里的leap或leaps不可改作jump或jumps。
（2）leap比较客观，jump比较主观。例如：We watched him leap across the brook. 和I was afraid to jump.
（3）leap着重在跳的距离或过程，jump着重在跳的动作。例如：We watched him leap across the brook. 和We saw him jump up and run away.
