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1) I was looking out of the window when I saw my aunt.

2) The boy was going by bus when the accident took place.

3) She was walking out when the snowstorm began.

4) My parents were travelling in Italy from August to September.

5) The sky was getting black.

6) Ann was coming very quickly when she heard someone cry.

7) Не was doing experiments when something went wrong.

8) We were climbing the mountain when night came.

9) The students were writing the paper from 5 p.m. to 7 p.m.

10) My grandparents were thinking of their past when I came in.