[单选题]Directions: In this part there is a sentence with four choices marked A, B, C and D. Choose the one that best completes the sentence.All the economists are working on （ ） the financial crisis can be prevented, which has caused a huge loss throughout the world.
A
how
B
when
C
that
D
why
正确答案：A
题目解析
分析句子可以确定which has caused a huge loss throughout the world为定语从句修饰先行词the financial crisis。而结合句意可知（ ）the financial crisis can be prevented应作on的宾语，为宾语从句。结合句意分析宾语从句中缺少方式状语，需要能引导宾语从句并且可以表示“怎样、如何”的how来引导，故选A。
