am wondering if we could go boating on the weekend. —It a good idea.

(2009浙江宁波质检)Since David ________ downloaded a virus into his computer, he can not open the file now．

The pictures about the city are not so amazing as about the countryside.

I think it’s necessary to learn how to work in groups. —I quite agree. Sometimes it’s even than grades.

Chinese students have than American students, so American studentsspend at school than Chinese students.