—Have you been to the Great Wall?—Perhaps not in my memory.________，it might have been during my early childhood.

If _____ without following the doctor’s instructions, the medicine may have serious side effects. 

I've tried very hard to improve my English.But by no means ________ with my progress.

_____ this afternoon, you would have to come again next week.

---Where did you fall in love with her at first sight? ---____was in a small villiage where my father worked.