Grammatical structure

Having watched a sample lesson the question asks what grammatical structure is being taught here;
the teacher sets a context of a rockstar and elicits the following sentences which he then drills
he drinks champagne
he drives a red ferrari
he lives in a castle
he has a lot of girlfriends
he goes on exotic holidays
then he "takes a lot of drugs" and goes to gaol then the teacher elicits the following sentences
He used to drink champagne now he drinks water
He used to drive a red ferrari now he walks etcetc .....
??
What grammatical structure is being taught here?
please help...