They can can what they can can,but can't can what they can't

问题描述:

They can can what they can can,but can't can what they can't

这是一个著名的绕口令:
意思是:他们可以把他们可以装罐的东西装罐,但他们不能把他们不能装罐的东西装罐.
can既有“能”的意思,又有“把……装罐”的意思.
两个what引导的都是宾语从句.