问题补充:
Some scientists believe that is no doubt a cure for AIDS will be found.
A. it; that
B. it; whether
C. there; that
D. there; whether
答案:
A. it; that
B. it; whether
(答案→)C. there; that
D. there; whether
解析:句意:科学家相信,毫无疑问,艾滋病的治疗方案终将被找到。Believe后面的that引导宾语从句,在从句中第一空用it做形式主语,that引导真正的主语。