Using FOR and SINCE

The main difference between these two forms is:

• FOR is used to express a period of time while SINCE is used to indicate the starting point in which the action began; go to this exercise to see it clear; click here

If you go to this link, you'll see a good explanation of these forms and take this sentence to be learnt by heart:

Just remember this sentence "For a period of time, since a point in time."

If you want to practise with some more exercises, here you are some links:

exercise 1      exercise 2       exercise 3     exercise 4 

If you are not sure about the tenses, you should revise the difference between passt simple and present perfect, a previous entry in this blog or go to these links:

exercise 1      use of how long with present perfect or past simple; click here

To finish with, pay attention to the pronunciation of SINCE  /SINS/