----- ----- ----- ----- the term ,we always clean our classroom.在学期末,我们总要打扫教室.

We clean our classroom in the afternoon(改为现在进行时） We（are）（cleaning）our classroom now. It's the o'clock.(对划线部分{the o'clock}

at the end of

At the end of
在...末

at the end of 在...结束时