Why couldn't he say something vital and original instead of just spouting the same old platitudes?

他为什么不能说点重要的、有新意的东西，而不只是喋喋不休地讲些陈词滥调呢？

What are you spouting on about now?

你这会儿又在唠叨什么呢？

He's always spouting off about being a vegetarian.

他老把自己吃素挂在嘴边。

He is always spouting Shakespeare.

他老是喋喋不休地谈莎士比亚。