我现在不能说话——我正在做饭。

I can't talk now - I ___am ___in ___the ___middle ___of cooking a meal.

但当我正在旅行时，我收到了另一封电子邮件。

But while I ___was ___in ___the ___middle ___of my tour, I received another e-mail.

她正在写报告。

She ___is ___in ___the ___middle ___of writing a report.