第一节单项填空（共15小题，每小题1分，满分15分）
从A、B、C、D四个选项中，选出可以填入空白处的最佳选项。
例：Stand over there ______ you’ll be able to see it better.
A. or B. and C. but D. while
答案是B。
1. I will never forget _______trip to the United States with my husband, which was really _______unforgettable experience for me.
A. the; an B. the ; / C. a ; / D. a, an
2. —Tony, why do you look so tired?
— I ________waste along the river for the past 6 hours.
A. picked up B. have been picking up C. was picking up D. had picked up
