我们正在上课，这时发生了地震。

We were having class when the earthquake broke out.

youdao

现在是九点钟，我们正在上课。

It's nine o 'clock. We are having classes.

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一位漂亮的女士把我们领到了化学实验室，在那儿，杰克逊先生正在上课。

A pretty lady led us into the chemistry lab, where Mr. Jackson was giving a lecture.

youdao

一位漂亮的女士把我们领到了化学实验室，在那儿，杰克逊先生正在上课。

A pretty lady led us into the chemistry lab, where Mr. Jackson was giving a lecture.

youdao