This is______difficult problem that few students can work it out.

---Have you got anything to do this afternoon, Lucy and Lily?---Yes, _________ of us are going to the home for the elderly.

 of them has known about this because it has been already reported on TV.

 David talked with a friend of ____ on the Internet for a long time yesterday.

— Which would you like to visit, Shanghai Expo Garden or Beijing Bird Nest? —           . I prefer to enjoy the 2010 FIFA World Cup at home.