Zhang Lin was addicted to computer games during his last year in high school , otherwise he ____________a student of Beijing University .
Mr Wang went to Nanjing ____ October,1998 and came back home ____ the morning of Nov.5.
We have produced 15% more cotton this year____ we did last year.
The teacher is busy ____ correcting papers.
____ the problem of method is solved, talking about the task is useless.
Where have you been ____ you left home?