21.　 This hair clip costs me five yuan. (划线提问)

20.　 Can I help you, Miss? (同义句)

19.　 Fangfang is helping Lili in the classroom. (划线提问)

18.　 He is fishing now. (用Sunday mornings改写)

17.　 Are those knives? Yes, they are. (单数)

16.　 There are some books on the table (否定句)

15.　 Does Simon close the door of his classroom? No, he doesn’t. (用now改写)

14.　 They don’t often travel in the country. (用these days改写)

13.　 He gets up at seven in the morning. (用at present改写)

12.　 Does she have sports on Monday? (用now改写)