--You’ve made great progress in your studies of English haven’t you? --Yes but much .A.

问题补充：

--You’ve made great progress in your studies of English, haven’t you? --Yes, but much .

A. remains to do

B. is remained to do

C. remains to be done

D. is remained to be done

答案：

A. remains to do

B. is remained to do

(答案→)C. remains to be done

D. is remained to be done

解析：remain作系动词用，本身不用于被动语态，有时与不定式的被动结构构成合成谓语，意为尚待。