I'm going to talk about 'need'. Do you know

the difference between 'needn't' and 'not need to'?

Look at these two sentences in the present - is the

meaning the same or different?

'You don't need to worry about the exam,

you've studied lots.'

'You needn't worry about the exam,

you've studied lots.'

They're the same right? Maybe 'needn't'

is a little bit more formal, but the meaning

is that there is 'no necessity for you to worry'.

Now look at these two sentences in the past:

'He didn't need to worry about the exam.

He had already passed the course.'

'He needn't have worried about the exam.

It was really easy.'

These are different! In the first sentence,

he had already passed the course, so he knew

he 'didn't need to' worry.

In the second sentence, he didn't know the

exam was going to be easy, so he was worried,

but he 'needn't have been'.