17c sky
18d suggest
19c because
20d since
II.1 takes
2 are working
3 didn't watch
4 was washing
5 have studied
6 will live
III.1 he was born in scotland
2 yes he did
3 medicine
4 one child
5 penicillin
6 in 1945
IV.1 the teacher told me that she/he was really happy about my improvement in english
2 I wish I had enough time to finish this work
3 it is interesting to go to the beach in such hot weather
4 are the animals usually fed three times a day?