Measures have been taken to prevent the accidents but much for more improvement.A. remai

问题补充：

Measures have been taken to prevent the accidents, but much for more improvement.

A. remains to be done

B. is remained to do

C. remains to do

D. is remaining to be done

答案：

(答案→)A. remains to be done

B. is remained to do

C. remains to do

D. is remaining to be done

解析：这题考察remain的用法：remain不及物动词，不用被动语态，remain to be done“仍然要被做”，句意是：防止事故已经采取了很多措施，但是还有很多事有待去做。选A。