The adverbs 在 / 正在
In Chinese, 在 (zài) and 正在 (zhèngzài) stand before a verb and show that the action is going on right now.
In English it corresponds to the present continuous.
This section shows three ways of expressing an action in progress.
Form 1: 在 / 正在 + verb
在 / 正在 + verb
Meaning:
is doing … right now
Form 2: 在 / 正在 + verb + 呢
在 / 正在 + verb + 呢
Meaning:
is right in the middle of doing …
Here 呢 underlines the ongoing situation.
Form 3: verb + 呢
Verb + 呢
This form also says the action is going on at this moment.
Negative form
没（有）is used to negate an action in progress.
没（有）+ verb
Meaning:
is not doing it
你还在读大学吗？
还háistill
在zàimarks the action as ongoing
读大学dú dàxuéstudy at university
学生们正在上课呢
在 and 正在 are interchangeable here:
学生们在上课呢。
学生们正在上课呢。
学生们 + 在 / 正在 + 上课 + 呢
the students + right now + have class + ongoing
学生们xuéshengmenthe students
上课shàngkèhave class
呢neunderlines the ongoing situation
我们读书呢
我们 + 读书 + 呢
we + read + ongoing
There is no 在 / 正在 here, but 呢 shows the action is under way.
In dialogue
你在做什么呢？
我正在看电视
正在 + 看电视
right now + watch TV
我去看电影，你去不去？
我在学习呢，不想去
在 + 学习 + 呢
right now + study + ongoing
你在买菜吗？
我没买菜，买水果呢
没 + 买菜
not buying groceries
买水果 + 呢
buying fruit
The rule in short
If the action is going on now
在 / 正在 + verb
or
在 / 正在 + verb + 呢
or
verb + 呢
Meaning:
is doing … right now
Negative
没（有）+ verb
Meaning:
is not doing it
Examples
我正在看电视
我在学习呢
我们读书呢
我没买菜