Future Perfect Continuous signal words
As far as Future Perfect Continuous Tense is concerned we can we can talk about such signal words as: FOR and SINCE. Of course these words can be also used with other tenses (especially Present Perfect Tense). They help to describe how long a specific activity will be done. The other characteristic expressions can include time phrases which can show when the activity will be finished eg. 'in 2015' or 'by the time you arrive' etc.