Uses of 'For' and 'Since'.

 Mainly, For and Since are used with the present perfect and the present perfect contiuous Tense. They are used as follow:

For: For is used with a period of time upto now. It is used to indicate the time of the beginning or the duration of the action. It is used before indefinite/uncertain period of time. 

'for' is used before-

Rule (1) : Numeral Adjective + minutes

for e.g.  (a) For thirty minutes

               (b) For many minutes

               (c) For several minutes

Rule (2) : Numeral Adjective + hours

for e.g.   (a) For two hours

                (b) For many hours

                 (c) For several hours

Rule (3) : Numeral Adjective + days

for e.g.    (a) For five days

                 (b) For many days

                  (c) For several days

Rule (4) : Numeral Adjective + weeks

for e.g.    (a) For two weeks

                 (b) For many weeks

                  (c) For several weeks

Rule (5) : Numeral Adjective + months

for e.g.    (a) For three months

                 (b) For many months

                 (c) For several months

Rule (6) : Numeral Adjective + years

for e.g.      (a) For five years

                   (b) For many years

                   (c) For several years

Rule (7) : Numeral Adjective + decades

for e.g.     (a) For three decades

                  (b) For many decades

                  (c)  For several decades

Rule (8) : Numeral Adjective + Centuries

for e.g.     (a) For two centuries

                  (b) For many centuries

                  (c) For several centuries

Rule (9) : A + minute

for e.g.  For a minute

Rule (10) : An + hour

for e.g.  For an hour

Rule (11) : A + day

for e.g.   For a day

Rule (12) : A + week

for e.g.   For a week

Rule (13) : A + month

for e.g.   For a month

Rule (14) : A + year

for e.g.    For a year

Rule (15) : A + decade

for e.g.    For a decade

Rule (16) : A + century

for e.g.   For a century

Rule (17) : A long period/ a long time/ ever/ a                      while/ a moment/ an era

for e.g  For a long time 

              For a while

              For a long time

              For a moment

              For ever

Rule (18) : The last/Past + Numeral Adjective + minute(s)/ hour(s)/ day(s)/ week(s)/ month(s)/ year(s)/ decade(s)/ century/centuries.

for e.g. For the last five hours

              For the past four days

               For the last six years

              For the past six years

Rule (19) : seasons

for e.g.  For two seasons

Rule (20) : Minutes/hours/days/weeks/months/years/decades/centuries

for e.g. For hours

              For years

             For months

             For weeks

Note: (i) Since is not used before Period of time + ago but for is used.

for e.g. (a) His brother has been ill for five days.

(b) His brother has been ill since five days ago.

(ii) For is not used with all + period of time

for e.g. (a) It has been raining all day.

(iii) For is used in sense of तक/ के िलए  in Tenses.

for e.g. (a) Binay waited for me for three hours.

(b) She goes there for two hours every day.

(c) My younger brother will be in Mumbai for the next five days.

Since: Since is used with some point of time in the past. It means from that point of time to the point of speaking. Since is used before:

Rule (1) : name of the days

For e.g.  Since Monday

                Since Tuesday

Rule (2) : name of the months

For e.g.  Since January

                Since February

Rule (3) : name of the years

For e.g.  Since 1980

                Since 1990

Rule (4) : name of the parts of the day

For e.g.  Since Morning

                Since noon

                Since daybreak

                Since dawn

                Since afternoon

                Since evening

                 Since night

                 Since midnight

                 Since sunrise

                 Since sunset

                  Since dusk

                  Since twilight

Rule (5) :  O'clock/a.m./p.m. 

For e.g. Since 5O'clock

               Since 6 a.m.

                Since 7 p.m.

                 Since 6:30 a.m.

Rule (6) : yesterday/ last night/ last week/ last month/ last year

For e.g.  Since yesterday

                Since last night

                Since last month

                 Since last year

Rule (7) : name of seasons

For e.g.  Since Spring

                Since winter

                 Since Autumn

                 Since summer

Rule (8) : name of festivals

For e.g.   Since Diwali

                 Since Id

                  Since Christmas

Rule (9) : name of events

For e.g.    Since arrival

                  Since his departure

                   Since his birth

                   Since his marriage

                    Since his death

                    Since their quarrel

Rule (10) : Stage of one's life

For e.g.    Since his childhood

                   Since your youth

Rule (11) : last+monday/tuesday.........etc., January/february.....etc., Spring/winter.......etc. or other time expressing words 

For e.g.   Since last monday 

                 Since monday last

                  Since last march

                  Since march last

                  Since last spring

                  Since spring last

                  Since last midnight

                  Since midnight last

Note: For is used before The last+ Time expressing words because it shows a period of time not a point of time.

For e.g.  (a) Since last week means A point of time about seven days ago.

(b) For the last week means the period of seven days just completed.