What Are Modals And Auxiliaries? Ielts English Grammar Preparation
1-To avoid repetition of a previous ordinary verb; as,
Do you know him? Yes, I do.
She sings well. Yes, she does.
You met him, didn’t you?
He eats fish and so do you.
2-To form the negative and interrogative of the simple present and simple past tenses of
ordinary verbs; as,
He dosen’t work.
He didn’t work.
Does he work?
Did he work?
(3)In the imperative, do makes a request or invitation more persuasive; as, Do be quiet,
Oh, do come! It’s going to be such fun.
In such cases do is strongly stressed.
(4) Do is also used to emphasize the affirmative nature of a statement; as,
You do look pale.
We asked them not to leave but they did left.
2-When Must, Ought to be used ?
i-Must Auxiliary verb is used to express obligation or necessity .
You must improve your spelling.
We must get up early.
(2)Must is often used when the obligation.
Must verb is commonly used when necessity comes from the speaker.
And When the obligation comes from somewhere else, have to is often used. Compare:
I must be on a diet. (It is my own idea.)
I have to be on a diet. The teacher has taught me how to read well.
(3) Must refers to the present or the near future.
To talk about the past we grammatically use had to
Yesterday we had to get up early.
(4) Must can also express logical certainty.
Living in such crowded conditions must be difficult. (=1 am sure it is difficult.)
She must have left already. (I am sure she has left already).
When Ought (to) be used ?
1-Ought (to) can also be used to express probability.
Prices ought to come down soon.
This book ought to be very useful.
2- Ought (to) expresses moral obligation or desirability; as,
We ought to love our neighbours.
We ought to help him.
You ought to know better.