rapidity
n. 迅速，速度
例句
The disease is spreading with alarming rapidity.
这种疾病正在以令人吃惊的速度蔓延。
《牛津词典》
The rapidity of the decline is as striking as its extent.
如此迅速的下滑，其程度令人震惊。
She afterward descended with so much rapidity that I lost my senses.
她后来下降的如此极速我失去了意识。
