apid a.迅速的,飞快的,急促的
这是一个正常形容词,可以修饰名词,可以做表语.
如：a rapid pulse过快的脉搏
rapid movements of a piston 活塞快速的运动
One local boater can attest to the risks associated with trying to run this rapid at high water.
Atrazine mineralization was as rapid in soils under a rotation
rapid后面所跟的介词是由介词后面的名词决定的,rapid本身没有固定搭配.