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

问题补充：

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

A. which

B. that

C. what

D. whether

答案：

A. which

(答案→)B. that

C. what

D. whether

解析：考查同位语从句。本题中的同位语从句that a cure for AIDS will be found.解释名词no doubt的内容。That在句中不充当任何成分，只起引导和连接作用。句意：一些研究人员认为，毫无疑问艾滋病的治愈方法将会被发现。故B正确。