第一部分 单项选择（共13小题：每小题1分，满分13分）
1. Do you still remember the difficulty you ______ the post office?
A. have found B. had finding C. have to find D. had to find
2.Some house plants grow better if placed near a window with plenty of sunlight ______ others prefer to be in a more shaded spot.
A. unless B. since C. when D. while
