那时我正在看书。

I was reading a book at that time.

坐在窗边的男人正在看书。

The homme sitting by the window is reading a book.

此时，她正在看书。

At this moment, she is reading a book.

那位男士正在看书。

That man is reading a book.

他昨天七点正在看书。

He was reading at seven yesterday.

你其时正在看书还睡着了。

You were reading and you fell asleep.

有一次我正在看书，忽然听到窗外有什么在叫。

Once when I was reading a book, I heard something calling outside the window.