Ответ:
1. When I went to work, I met my old friend, but couldn't talk to him as he was in a hurry.
2. What were you doing yesterday at this time? I called you twice, but no one answered. - I was cooking dinner.
3. What language does this foreigner speak? - He speaks German.
4. This writer speaks four languages perfectly.
5. My brother was playing the piano when the door opened and someone called him in a low voice.
6. I know that when we come to Boris, he will still sleep.