Bonjour,
present perfect en be + V-ing.
=> have/has been + V-ing
Réponse :
a. They have been waiting for him to finish his tower for six hours now.
b. He has been repairing his model since this morning!
c. What has Peter been doing? I think he's working on a plane model.
d. He has been painting his boat: he is covered in paint.
e. His model has been standing here too long, it's dusty!
f. He has been looking forward to exhibiting his model.
;)
