急速的英文：
quickness
rapidity

参考例句：

Rescue workers rushed to the site of the plane crash.
救护人员急速赶到飞机坠毁的现场.

The dancer's breathing quickened as she approached the end of her solo.
舞蹈家在接近她独舞的尾声时呼吸变得急速了。

A rapid swimming stroke consisting of alternating overarm strokes and a flutter kick.
自由式游泳以双臂呈圆形交替的动作与急速的双腿蹬踢形成的快速游泳法。

The carriage rolled rapidly onward.
马车急速地行驶着。

Relief supplies were rushed in.
救济品已急速送到。

Rocket Power Beach Bandits
急速动力-沙滩强盗

The train rocketed downhill.
火车急速滑下坡。

The car was running at high speed.
汽车急速地向前行驶。

Make haste; hurry up
急速;赶快;加速

To shake rapidly;jiggle.
急速摇摆;摇铃

quickness是什么意思：
n. 急速,迅速,速度

"Quick at meal, quick at work"
吃得快,做得快

Quick decision is characteristic of him.
快速决定是他的特征。

He runs as quick as a deer.
他跑得跟鹿一样快。

Be slow to promise and quick to perform
不轻诺,诺必果

A quick survey or glance.
快速的浏览或瞥视

rapidity是什么意思：
n. 迅速,急速,速度

run the rapids.
冲过急流

biological section rapid treater
生物切片快速处理仪

shooting the rapids in a ruBBer raft.
使橡皮充气船快速行驶

The currency has devalued at a rapid rate.
货币已经以很快的速度贬值了。

The rapid change has been astounding.
巨大的改变已令人吃惊。