26. The news that scientists so far haven’t found out the cause of bird flu discouraged so

问题补充：

26. The news that scientists so far haven’t found out the cause of bird flu discouraged some WHO officials,?

A. didn’t they

B. did it

C. didn’t it

D. did they

答案：

A. didn’t they

B. did it

(答案→)C. didn’t it

D. did they

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