This kind of exercise is most and therefore is a good test of your students’ ability.A.

问题补充：

This kind of exercise is most , and therefore is a good test of your students’ ability.

A. surprising

B. encouraging

C. exciting

D. challenging

答案：

(答案→)A. surprising

B. encouraging

C. exciting

D. challenging

解析：考查形容词的用法：A. surprising惊人的，B. encouraging令人鼓励的C. exciting令人兴奋的 D. challenging有挑战的，句意是：这种练习是最有挑战的，因此是检测学生能力的很好的办法。选A。