Modals Verb and Nouns

We _____________ more worried about the environment.
ought to being
have to being
has to be
ought to be

You __________ yell, I _______ hear you just fine.
doesn’t have to / may
won’t / won’t
shall / mustn’t
don’t have to / can

A: Do you know where Steven was last night?
B: I’m not sure. I think he ___________ at the feast last night.
must have been
may be
can be
might have been

A: _____________ the car in front of your house for a while?
B: Certainly.
May I park
Shall I parked
Shall I park
May I parked

A number of _______ ________ expressed interest in participating the seminar.
person / have
people / has
person / has
people / have