问题
, I lost heart in English learning, but my teacher often said to me, “Keep on studying hard ,and you’ll succeed .”[ ]
A: At one time; in time
B: At one time; on time
C: At a time; in time
D: At a time; on time
B: At one time; on time
C: At a time; in time
D: At a time; on time
正确答案是：
