1) We are back at our desks again because the summer is over.
2) We learned many interesting things about the towns in which we stopped.
3) Yes, we did.
4) when the weather was cold, we stayed at home or went to the cinema.
5) They went on an excursion to the mountains.
6) They decided to put up a tent.
7) They begin digginf because they couldn't drive the tent pole into the ground.
8) They found something like a box in the ground.
9) Yes, they did.
10) They showed it to the scientists.
11) They'll talk about the wonderful time they had this summer.
12) Nick and his family have been to many interesting places on the Volga.