问题描述：
| This kind of exercise is most _____, and therefore is a good test of you students' ability. |
| [ ] |
| A. surprising B. encouraging C. exciting D. challenging |
考点提示：形容词
最佳答案： | D |
This kind of exercise is most _____, and therefore is a good test of you students' ability.
This kind of exercise is most _____, and therefore is a good test of you students' ability. [ ]
最佳答案： 