English - Grammar - Verb Tenses - Perfect continuous tenses - Three Perfect Continuous Tenses

6 steps: (1) Perfect continuous = have/had/will have + been + verb-ing. Shows DURATION of an ongoing action. (2) PRESENT PERFECT CONTINUOUS: have/has been + -ing. 'I have been studying for 3 hours.' = started in past, still going NOW. (3) PAST PERFECT CONTINUOUS: had been + -ing. 'She had been waiti