在我加入绿色集团的时候，他们已经作为志愿者打扫图书馆两年了。

By the time I joined Greener Group, they had cleaned the library as volunteers for 2 years.

youdao

第四幅图片的内容： 同学们在打扫图书馆。

What are they doing?S: They are cleaning the library.

youdao

我们要打扫图书馆。

We need to clean the library.

youdao

让我们快一些。麦克和我今天值日。我们要打扫图书馆。

Let's hurry. Mike and I are on duty today. We need to clean the library.

youdao

让我们快一些。麦克和我今天值日。我们要打扫图书馆。

Let's hurry. Mike and I are on duty today. We need to clean the library.

youdao