问题
What’s wrong with you, MrKeller? — I’ve had a very bad headache for two daysAt first, I ______ I caught a cold, but the medicine ______
A:thought, hasn’t worked
B:had thought, didn’t work
C:thought, hadn’t worked
D:have thought, hasn’t worked
B:had thought, didn’t work
C:thought, hadn’t worked
D:have thought, hasn’t worked
正确答案是：
