Scientists have come to the conclusion the temperature on Earth is getting higher and high

问题补充：

Scientists have come to the conclusion the temperature on Earth is getting higher and higher.

A. what

B. that

C. which

D. when

答案：

A. what

(答案→)B. that

C. which

D. when

解析：考查从句，从句the temperature on Earth is getting higher and higher不缺少成份，what表示…东西，可以做主语、宾语、表语；which表示哪一个，可以做宾语和主语；when关系副词，表示时间；that只起引导作用，不做成份，所以选B