我在上课。
Wǒ zài shàngkè.
I'm in class.
我们上课了。
Wǒmen shàngkè le.
Class has started.
老师在上课。
Lǎoshī zài shàngkè.
The teacher is teaching.
他今天要上两节课。
Tā jīntiān yào shàng liǎng jié kè.
He will teach two classes today.
