1B1 Present Perfect Continuous

Dear students,
have a look at this exercises, do it to reinforce the structure, you didn´t get it very well this afternoon,
http://www.englishpage.com/verbpage/presentperfectcontinuous.html
http://www.englishpage.com/verbpage/verbs7.htm
http://www.englishpage.com/verbpage/verbs8.htm