There is no doubt the world climate has been changing in recent years.A. thatB. whatC. if

问题补充：

There is no doubt the world climate has been changing in recent years.

A. that

B. what

C. if

D. whether

答案：

(答案→)A. that

B. what

C. if

D. whether

解析：考查固定句型：There is no doubt that 毫无疑问做某事。句意：毫无疑问世界气候在最近几年一直在变化。故选A。