conjunction
1
BAD : The Japanese have a tendency to keep silent while meetings.
GOOD : The Japanese have a tendency to keep silent during meetings.
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While (conjunction) introduces a clause: 'While we were on holiday, we did a lot of walking.'
During (preposition) introduces a noun phrase: 'During the holiday we did a lot of walking.'
2
BAD : While I drove to the airport, my car broke down.
GOOD : While I was driving to the airport, my car broke down.
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To refer to a 'background action', use the past progressive tense
( was /were doing ): 'While I was having a bath, the telephone rang.'
3
BAD : Who will look after the children while you will be at work?
GOOD : Who will look after the children while you are at work?