For this unit Refers to Student’s Book pages Writing headlines

between possibility and ability using examples: 
You can/may leave
 = possibility 
(or permission); 
It may/might/could rain 
= possibility (or probability); 
I can swim 
= ability). 
 Answers
Possibility
could
Ability
can
Giving advice/recommendation 
should
had better
Necessary
must
have to
need to
Not necessary
don’t have to
    e 
Students work individually to correct the mistakes and then check their answers 
in pairs. When you go through the answers with the class, ask why they are 
incorrect.
 Answers
2  must to 
4  need needs to
3  has had better  5  might to
Language note
The mistakes in Exercise 2e are all connected with the form of modal verbs and 
semi-modals. 
English has eight true modal verbs (can, could, may, might, shall, should, will, 
would), which share the following four characteristics:
They form negatives with 
n’t
 (or 
not
), rather than 
don’t
, 
doesn’t
 … etc. 
I can / 
I can’
t
There is no 3rd person 
s
: 
I can
 / 
he can
.
There is simple inversion of subject and verb for questions: 
I can 
/
 Can I?
They are followed by a verb in the infinitive without 
to
: 
I can swim
.
Semi-modals (
ought
, 
had better
, 
need
, 
have to
, etc.) have a meaning similar to 
true modals, but do not share all the characteristics:
Ought
 is followed by 
to
, although this may be omitted in negatives and questions 
(
Ought I go?
)
.
Had better
 is much more common in spoken language 
we’d better hurry
.
Need
 is usually followed by an infinitive with 
to
, except in some idiomatic 
expressions (
I needn’t have bothered, Need I ask?
 etc.).
Have to
 acts as a normal verb, and has none of the four characteristics of modals 
listed above.
    f 
Students role play the meeting in groups of up to six. Encourage them to use the