GRAMMAR: How to use the present perfect continuous tense

source: BBC Learning English      2015年7月14日
Learn English grammar with Catherine and Finn as they explain how to use the present perfect continuous tense in 6 minutes. For extra activities and study materials on present tenses visit:
http://www.bbc.co.uk/learningenglish/...

# click this line for more grammar videos on present perfect vs. present perfect progressive vs. simple past