2.David said that it was because of his strong interest in literature _____ he chose the course.

　　A. that B. what C. why D. how

　　3. Engines are to machines ____ hearts are to animals.

　　A. as B. that C. what D. which

　　4. Some researchers believe that there is no doubt ___ a cure for AIDS will be found.

　　A. which B. that C. what D. whether

　　5. I was surprised by her words, which made me recognize ___ silly mistakes I had made.

　　A. what B. that C. how D. which

　　参考答案

　　1.D 2.A 3.C 4.B 5.A