Ответ:

1. saw, was cycling

2.were preparing, started

3.left,arrived

4.were walking, heard

5.didn't eat, were staying

6.drank, was not looking

7.dropped, was putting

6.met, was waiting

1. I SAW (see) Henry as I WAS CYCLING (cycle) to the sports centre.

2. While we WERE PREPARING (prepare) the picnic, it STARTED (start) to rain.

3.All my friends WERE LEAVING (leave) the party when I ARRIVED (arrive)

4. As we WERE WALKING (walk) by the river, we HEARD (hear) a shout.

5.We DIDN'T EAT (not eat) very much while we WERE STAYING (stay)in that hotel.

6.I DRANK (drink) my dad's coffee while he WASN'T LOOKING (not look)

7. She DROPPED (drop) her new phone as she WAS PUTTING (put) it in her pocket.

8. I MET (meet) a really interesting person while I WAS WAITING (wait) for the bus.