Complete the sentence with the correct words considering what you learned in lesson 7 - Past Perfect Continuous and Present Perfect Continuous.
I'm terribly sorry! _______ for a long time?
a. You have been waiting
b. Have been you waiting
c. Have you been waiting
The correct completion of the sentence is:
c. Have you been waiting
So the full sentence would be: "I'm terribly sorry! Have you been waiting for a long time?"