For, Since, Ago

For, Since, Ago

for and since

- For(일정한 기간)

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월요일       화요일       수요일

  10 minutes, an hour, a week, a month, five years, two hours, four weeks, six months, a long time

  He has been in Canada for six months

  We have been waiting for two hours.

- Since(시간한 기간을 의미)

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월요일 부터 ~~~ 

  monday, 9:00, wednesday,, my birthday, 

  He has been in Canada since January.

  We have been waiting since 9:00

- Ago(Before now)

She stared her new job three weeks ago.

When did Tom leave ? Ten minutes ago

I had dinner an hour ago.

Life was very different a hundred years ago.

Compare ago and for

When did she arrive in Brazil ? 

  She arrived in Brazil three days ago.

How long has she been in Brazil ?

  She has been in Brazil for three days.