1. _____ is known to the world, China’s Liu Xiang became the first Asian in history to win the men’s 110m hurdles at the Olympic Games. 

   A. That         B. Which           C. As         D. It

2. Living in the Central American desert has its problems, _____ obtaining water is not the least.

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

3. I don’t know the reason _____ you were absent from the meeting, but I am sure that someone will tell me the reason _____ you haven’t told me.

   A. why; that                 B. that; why       

   C. because; which            D. of which; that

4. When she came back from abroad, Lucy told us about the cities and the people _____ she had visited.

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