1. Jane (had learnt) a lot of things about animals by Friday.
2. The students (had prepared) for the trip by that time yesterday.
3. I was surprised, because I had never (seen) a grizzly bear.
4. The forest was full of rubbish. Somebody (had thrown) it.
5. When the students (returned) their friends (had gone) away.
6. When we (reached) the forest the travellers had already (camped).
7. The students (had solved) some ecological problems in the camp by Sunday.