---John, how did your English exam go?---I thought I ____, but in fact I came in the top 10% in the class.
—Those are size 44. You might need a smaller size. —Yes, I ______ a bit of weight. I have been trying to lose weight!
—How did you do in the driving test yesterday? —I had a narrow ______. My month-long practice gave me some comfort.
—The accident might not have happened, had we been more careful. —But we ______.
—This returned scholar has become one of the top experts in this field. —Yes, I know him very well. He ______ for ten years at an institute in the USA. A. has worked B. has been working C. worked D. had worked
— Why are you so popular with your students? — As a teacher, I seldom give my students so difficult a problem ____ they cannot work out.