The Perfect Progressive Tense shows action or existence began before the time referenced and may or may not continue after the time referenced. This refers to action or existence happening over time after it has begun but before it has finished, like a mid-point. The auxiliaries to have and been (a form of to be) are combined with the present participle (V-ing) of the verb.

• Past Perfect Progressive – Action that had been continuing over time to a point in the past.
• Present Perfect Progressive – Action that has been continuing over time to the present moment.
• Future Perfect Progressive – Action that will have been continuing over time in the future.

Past Perfect Progressive	had been + (V-ing)	By the time WWII started, Farmer Tweedy had been raising chickens for 12 years.
Present Perfect Progressive	have/has been + (V-ing)	Nellie and Norbert have been skiing for 6 years. Fido has been chasing the neighbor’s cat for hours.
Future Perfect Progressive	will have been + (V-ing)	By next June, Natalie and Pete will have been dating for 33 years.

VERB TENSES - COMPLETE VERB