【题目】Even though we have made much progress in preventing pollution, yet much ________.
A. is remained to doB. remains being done
C. remains to be doneD. is remained to be done
在线课程【答案】C
【解析】
试题分析：句意：虽然在防治污染方面我们已经取得了很大进步，但依然还有许多要做。remain to do这里需要用它的被动式remain to be done，故选C。