he field research will take Joan and Paul about five months; it will be a long time _______ we meet them again.
This is a city which lives for today while ____ by its past.
In September 2008,China’s key milestone in space travel _____when Zhai Zhigang conducted the first space walk.
We _____ last night,but we went to appreciate the flowerbeds and streetlights in Tian’anmen Square instead.
Each of us, ____old or young,is a valuable member of society.
If a computer crashes,you will lose the file you _____ on unless you save it regularly.