教授的讲座变成了一通冗长乏味的说教，学生们都开始打瞌睡了。

The professor's lecture turned into a long ___screed that made all the students yawn.

工人在抹灰前先固定好找平层以确保墙面平整。

The worker fixed the ___screed before plastering to ensure the wall surface was level.