—Do you think yesterday’s math problem was difficult? —Yes. I could ________ work it out.
—Mum, I’ve heard that we can’t eat ____ these days. Is it true?—Take it easy. It is safe to eat cooked meat.
Boys, don’t lose____ in playing Angry Birds. It is bad for your eyes to play computer games for a long time.
—What do you want to be in the future, Lucy?—I want to be _____ pilot. It is _____exciting job.
New technology____________to stop the students from cheating in the exam last year.A. is used B. used C. was used
--Why are the windows so dirty?--Because we_________them for a long time.A. have cleaned B. haven't cleaned C. didn't clean