Present perfect continuous - 3
Exceptions in spelling
- Final 'e' is dropped (but 'ee' is not changed): come-coming, but agree-agreeing
- After a short stressed vowel, final consonant is doubled: sit-sitting
- A 'l' as last consonant is doubled: travel-travelling
- Final 'ie' becomes 'y': lie-lying
Whether you have to use “since” or “for”.
- since: if the starting point is given (two o’clock, last Friday, 1998)
- for: if the period of time is given (twenty minutes, two days, one year)
Examples:
- I have been waiting since 4 o’clock.
- Sue has only been waiting for 20 minutes.
- Tim and Tina have been learning English for six years.
- Fred and Frida have been learning French since 1998.
- Mary has been saving her money for many years.