– You must have your work done within 2 days. Finishing a task in such short time is a

问题补充：

– You must have your work done within 2 days.

-- Finishing a task in such short time is a (an) .

A. conclusion

B. challenge

C. explanation

D. approach

答案：

A. conclusion

(答案→)B. challenge

C. explanation

D. approach

解析： 略