两道英语句子改错

1. as usual 固定搭配，“同往常一样”
2. the teacher lets us listen to him. let第三人称单数，应该加“s”，固定用法为“let sb. do sth.”,所以要去掉to

as usual
lets->asks

as usual,固定用法，和平时一样。
lets 改成 let ,let是情态动词，没有人称和数的变化。另外那个to 也要去掉，情态动词后面用动词原型。
the teacher let us listen to him.

as去掉

lets->asks