1- We knew we had to arrive by nine.
NECESSARY
We knew that .................................................... by nine.
it was necessary to arrive
Dave prefers eating sandwiches to a proper meal.
RATHER
Dave .................................................... than a proper meal.
would rather eat sandwiches
They will expect you to wear a suit for the interview.
HAVE
You …………………………………………... a suit for the interview.
'll have to wear
will have to wear
They weren't allowed to stay out late when they lived with their parents.
LET
Their parents .................................................... stay out late when they lived at home. 
would not let them
wouldn't let them
did not let them
didn't let them
I prefer to arrive an hour early.
RATHER
I .................................................... an hour early.
would rather arrive
'd rather arrive
He couldn't swim until he was in his twenties.
ABLE
He .................................................................. until he was in his twenties.
wasn't able to swim
was not able to swim
Because of the snow, we weren't allowed to take the mountain road.
LET
Because of the snow, the police .................................................... the mountain road.
would not let us take
wouldn't let us take
I went to the office then remembered it was my day off.
HAVE
I ......................................................... to the office as it was my day off.
need not have gone
We got a table at the restaurant without a reservation.
NEED
We ............................................................ book a table at the restaurant.
did not need to
didn't need to
It was careless of him to go without checking the times.
OUGHT
He .................................................... the times before going.
ought to have asked
ought to have asked me
Perhaps we missed the correct turning.
MIGHT
We ......................................................................... the correct turning
might have missed
might've missed
You were expected to answer all the questions on the exam paper.
ANSWERED
You ............................................................. all the questions on the examination paper.
should have answered
should've answered
"Is Andy accustomed to the climate yet?"
USED
"Has Andy .................................................... yet?"
got used to the climate
gotten used to the climate
-I'm afraid you can't smoke in here.
ALLOWED
You ..................................................... in here.
are not allowed to smoke
're not allowed to smoke
aren't allowed to smoke