1. China’s population is expected to increase to about 1.5billion in 2040,           it will start to decline slowly.

A. where                B. after which          C. on which         D. which

2. Doctors are concerned that the children           too much time in front of the TV don’t get enough exercise.

A. those spend          B. who spend            C. to spend         D. spend

3. We walked along the beach looking for a spot to sit,           we could have a good talk.

A. where                B. which                C. when             D. that

4. As I arrived in Sydney, I wanted to see everything on my first day,          I knew was impossible.     A. that                B. where                C. when             D. which