问题

He _______ English by making word cards. But now he _____ it by listening to tapes.
A:used to learn is used to learn
B:is used to learn used to learn
C:is used to learning used to learn
D:used to learn is used to learning;
B:is used to learn used to learn
C:is used to learning used to learn
D:used to learn is used to learning;
正确答案是: