1. By the time you arrive in London, we _____ in Europe for two weeks.

A. shall stay       B. have stayed      C. will have stayed      D. have been staying

2. I appreciated ____ the opportunity to study abroad two years ago.

A. having been given     B. having given    C. to have been given   D. to have given

3. Living in the central Australian desert has its problems, _____ obtaining water is not the least.

A. of which     B. for what    C. as    D. whose