参考答案：
1. (1) countries (2) people (3) paper (4) babies (5) leaves (6) policemen (7) children (8) housework (9) knives (10) photos (11) teeth (12) foot (13) news (14) pages (15) clothes
2. (1) five centuries (2) twelve months (3) a lot of mice (4) Women’s Day (5) some watches (6) twenty deer (7) two pairs of trousers (8) ten pieces of paper (9) children’s stories (10) girl student
3. (1)—(5) DBADA (6)—(10) BCBAB