How long have you been waiting for the beginning of the concert?
How long has she been typing letters to her boss?
How long have you been swimming in the swimming pool?
How long has Alan been listening to his music in his room?
How long have they been discussing a new project?
How long have you been waiting for the beginning of the concert?
How long has she been typing letters to her boss?
How long have you been swimming in the swimming pool?
How long has Alan been listening to his music in his room?
How long have they been discussing a new project?