6. I really don’t know the reason for which she is absent today. ( ) 7. The bus won’t depart until there is enough passengers. ( ) 8. My homeworks is very long, so I can’ finish it tonight. ( ) 9. Why don’t you ask your parents for permission? ( ) 10.Physics are a very difficult subject, so you must try more. ( ) 11.How many day a week does she go to work, Peter? ( ) 12.It often takes me about 20 minutes finish this kind of work. ( ) 13.I’m very happy to give you an advice. ( ) 14.Do you remember the village where she was born? ( ) 15.Sorry, I don’t know what happened at the meeting last week. ( ) 16.He saw this play last night, wasn’t he? ( ) 17.He has got many more money than his sister, hasn’t he? ( ) 18.I have waited for you here for over 45 minutes. ( ) 19.Linda’s and John’s cars are very expensive, aren’t they? ( ) 20.If I knew he was sick, I would have visited him. ( )