Linking past actions

Interrupted actions in progress

The Past Continuous is often used when one action in progress is interruped by another action in the past. We usually use when or while to link these two sentences.
1. Sentence in Past Continuous + WHEN + Sentence in Past Simple
e.g. I was singing -------------------- e.g. my wife came home

2. WHEN/WHILE + Sentence in Past Continuous + Sentence in Past Simple
e.g. I was singing -------------------------- e.g. my wife came home

• I was talking with James when the telephone rang.
• While Angelica was playing tennis, the plane crashed .
• When Bob was painting windows, it started raining.

Fuente: http://www.englishtenses.com/tenses/past_continuous