6. I (cook) while my sister (wash up) 7. She (sleep) at 9 o ^ clock yesterday. 8. I (write) a letter yesterday. 9. When the iesson (begin). all the pupils (sit) at their desks. 10. He (write) this novel many years ago ...

I was cooking while my sister washed up

She was sleeping at 9 o ^ clock yesterday

I wrote a letter yesterday.

When the lesson begins all the pupils sit at their desks./When the lesson began all the pupils sat at their desks.

He wrote this novel many years ago ...