It is said that many kids are worried about the year 2012, they think the earth will be destroyed by disasters.
— Why do you look so worried? —My computer broke down and my essay ______ unfinished since.
By no means ______ true that all English people know their own language well.
Was it in 1969 ________ the American astronaut succeeded ________ landing on the moon?
It was not until she collected enough material to create her new novel.
If our time is usefully employed, it will _____ some useful and important products.