Exercise 19
1 a cooperation b cottage c column d conscious
3 a illegible b level c metal d illegal
5 a sunlight b sunlit c brightness d mind
7 a union b uniform c rumour d university
10 a unify b appetite c magnify d utility
Exercise 20
2 a diving b discover c discipline d divide
Exercise 21
3 a chemist b chicken c church d century
6 a chalk b champagne c machine d ship