Leslie Linguo

ESL Grammar Course

...to help you in your conversations with Leslie Linguo
The Modal Verbs Must and Should
SHOULD and MUST are modal verbs. We saw how to make correct sentences with modal verbs. In this unit we will see WHEN you can use them.

SHOULD and MUST have the same kinds of meaning, but MUST is always stronger.

Firstly, MUST expresses prohibition or obligation.

You MUSTN'T walk on the grass.
You MUST study for the exam.
Parking permits MUST be displayed in car windows.

SHOULD does not express prohibition or obligation; the phrase "you SHOULD study" is advice.

When giving advice or expressing necessity we can use both MUST and SHOULD.

- Do you think we SHOULD take our coats?
- Yes, you MUST; it might be very cold.
You SHOULD never cross the road without looking.
I'm afraid we really MUST go now.

In the past, use only SHOULD.
You SHOULDN'T HAVE BEEN so rude. It was bad of you.
They SHOULD HAVE TOLD him. Why didn't they?

When we use MUST in the past, we are expressing probability.
They MUST HAVE GONE home. (I feel sure that they have gone home.)

NOTICE that We can also use HAVE TO, NEED TO and NEEDN'T and sometimes WOULD to express advice and necessity. In unit 35 we will see the differences in the meanings of all these verbs.

An interesting use of MUST and SHOULD is to express probability.

It must be terrible to be in an earthquake.
There must be some mistake.
I can't believe it, I must be dreaming. It's five o'clock so he should be in his office. You shouldn't have any problems.

For strong negative probability use CAN'T.

I can't see them anywhere. They MUST HAVE GONE home.
They CAN'T HAVE GONE home because I saw them just now.

NOTICE that OUGHT TO means the same as SHOULD.
The Basic Sentence
Unit 1: The Basic Sentence
Unit 2: The Subject
Unit 3: The Verb
Unit 4: Subject and Verb
Unit 5: Negative Sentences
Unit 6: Short Forms
Unit 7: Word Order
Unit 8: Question Words
Unit 9: Making Questions
Unit 10: Subject Questions
Unit 11: Short Answers
Unit 12: Question Tags
Unit 13: Indirect Questions
Unit 14: Verb Forms
Unit 15: Using Verb Forms
Unit 16: The Verb to Be
Unit 17: Auxiliary Verbs
Unit 18: The Imperative
Unit 19: Present Simple Formation
Unit 20: Using the Present Simple
Unit 21: The Past Simple
Unit 22: The Present Continuous
Unit 23: The Past Continuous
Unit 24: Present Perfect Formation
Unit 25: Using the Present Perfect
Unit 26: The Past Perfect
Unit 27: Modal Verbs
Unit 28: The modal verb CAN
Unit 29: The modal verb COULD
Unit 30: The modal verbs MAY and MIGHT
Unit 31: The modal verbs WILL and SHALL
Unit 32: The modal verb WOULD
Unit 33: The modal verbs MUST and SHOULD
Unit 35: Necessity and Advice
Unit 37: GOING TO
Unit 38: USED TO
Unit 39: Verbs and Present Time
Unit 40: Verbs and Past Time
Unit 41: Verbs and Future Time
The Passive
Unit 42: Passive Sentences
Unit 43: Passive Verb Formations
Unit 44: Using the Passive
The Noun Phrase
Unit 45: Nouns and Noun Phrases
Unit 46: Plurals of Unit Nouns
Unit 47: Mass Nouns
Unit 48: Proper Nouns and Verbal Nouns
Unit 49: Genetive
Unit 50: Personal Pronouns
Unit 51: A, AN, SOME and ANY
Unit 52: THE
Unit 53: Nouns without A or THE
Unit 54: The Correct Article
Unit 56: Mass and Unit in Sentences
Unit 57: Quantity
Unit 59: ONE
Unit 60: Relative Clauses
Types of Sentences
Unit 61: Empty Subjects
Unit 62: Simple Sentence Types
Unit 63: Complex Sentence Types
Adjectives and Adverbs
Unit 64: Adjectives and Adverbs
Unit 65: Position of Adjectives
Unit 66: Position of Adverbs
Unit 67: Some Important Adverbs
Unit 68: Forms for Comparison
Unit 69: Comparing Two
Unit 70: Comparing Three or More
Unit 71: Adverbs of Time
Unit 72: Prepositions of time
Unit 73: How Often?
Unit 74: In the World
Unit 75: In a Town
Unit 76: Outdoors
Unit 77: Indoors
Unit 78: In a Room
Unit 79: Objects and People
How and Why?
Unit 80: How?
Unit 81: Purpose and Use
Unit 82: Reason and Consequence
Connecting Ideas
Unit 83: Similar Ideas
Unit 84: Opposite Ideas
Unit 85: Sequence of Events
Unit 86: Conditions