Pag.202 n.4

b) Your car could be in the car.
c) They have probably sold their house.
d) Maybe I won't come to your party tonight.
e) All the lights are off- perhaps she is in the bed.
f) I might apply for that job.
g) Laura has possibly left her books on the bus.
h) We may join you later in the pub.

Pag.204 
n.5

b) We ought to take exercise once a day.
c)She said we should use a comfortable chair and desk.
d) There ought not to be any music, radio or TV or any other distraction while we study.
e)We oughtn't to study late at night.
f) Regarding study techniques, you had better read the text once without marking it.
g)You had better make brief notes of the main points from memory.
h)The teacher said we ought to keep notes for easy reference.

n.6

b) They mustn't park them in front of the hotel.
c) Guests can't make loud noise in their rooms after 10 p.m.
d) Guests can order meals in their rooms.
e) To do this they must call the reception.
f)Guests  must leave their rooms by 11 a.m.
g)If guests leave the hotel before 7 a.m., they must settle their bill the evening before.
h) Guests can keep small dogs in their rooms.