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ลำดับตอนที่ #22 : For and Since (time)

For + period (5 minutes, 2 weeks, 6 years). For means 'from the beginning of the period until the end of the period.'

Since + point (9 o'clock, 1st January, Monday). Since means 'from the point in the past until now.'

for a period (from start to end) >|||||||||||||<	since a point (up to now) X======>
All tenses	Perfect tenses
for... 30 minutes ten days 6 months 2 years 3 centuries a long time ever etc	since... 10am Tuesday August 1998 I was young I left school the beginning of time etc

For can be used with all tenses. Here are a few examples:

• I study french  for 2  hours every day.
• They are studying for three hours today.
• He has lived in New York for 8 years.
• He has been living in Bangkok for three months.
• I worked at this school  for four years.

For is not used with 'all day'/'all the time' etc.

• She was there all day. (not 'for all day')

Since is normally used with perfect tenses:

• Peter has been here since 10am.
• He has been working since he arrived.
• I had lived in New York since my childhood.

Since can also be used in the structure 'It is (period) since...':

• It is a year since I saw her.
• How long is it since you got married?