—What are you doing this Saturday?—I'm not sure, but I ________ go to the Rolling Stones concert.
I was watching the news on TV ________ the power went off.
—How long will it be ________ the 30th Olympic Games is held in London? —It won’t be two years, I think.
When first ________ to the market, the computer software . was not a success due to its complexity in operation.
Have you ever wondered why some of the smartest students in your class sometimes ________ failing exams?
In 1986, the Chinese government ________ a law stating that by the year 2000 every Chinese child would have nine years of compulsory education.