Anglais • 1ère

Semi-modals (Have to, Need to, Be Able To)
The Verbal Group - Modal Auxiliaries and Semi-modals

Semi-modal Auxiliaries Overview
⚡ Semi-modal Auxiliaries
Have to, Need to, Be Able To
OBLIGATION
✅ have to do
✅ need to do
📝 have to work
ABILITY
✅ be able to
✅ be unable to
📝 be able to swim
🎯
Definition: Semi-modals function like modals but follow different grammatical patterns.
📚
Have to: Expresses external obligation (school rules, laws, etc.).
🔄
Need to: Expresses necessity or requirement.
💡
Be able to: Expresses ability as an alternative to "can/could".
💡
Tip: "Have to" vs "must" - "have to" is external, "must" is internal
🔍
Attention: Semi-modals use "to" before the main verb
⚡
Rule: "Be able to" can be used in all tenses unlike "can/could"
📋
Method: Practice with real-life situations for each semi-modal
HAVE TO
Present: have to
Past: had to
Future: will have to
NEED TO
Present: need to
Past: needed to
Future: will need to
BE ABLE TO
Present: am/is/are able to
Past: was/were able to
Future: will be able to
NEGATIVE FORMS
don't have to
don't need to
am/is/are not able to
Have To Exercises
1 Expressing External Obligation
Instructions :

Complete the sentences with "have to" in the appropriate tense.

Step 1: "Students ___ wear uniforms" (have to)

Present obligation → Use "have to"

Complete: "Students have to wear uniforms"

Step 2: "Yesterday, we ___ finish the project" (had to)

Past obligation → Use "had to"

Complete: "Yesterday, we had to finish the project"

Step 3: "Tomorrow, I ___ attend the meeting" (will have to)

Future obligation → Use "will have to"

Complete: "Tomorrow, I will have to attend the meeting"

Step 4: "Drivers ___ stop at red lights" (have to)

Legal requirement → Use "have to"

Complete: "Drivers have to stop at red lights"

Step 5: "Last year, employees ___ work overtime" (had to)

Past requirement → Use "had to"

Complete: "Last year, employees had to work overtime"

Answers :

1. have to, 2. had to, 3. will have to, 4. have to, 5. had to

Have To Rules :

• Present: Subject + have to + base verb

• Past: Subject + had to + base verb

• Future: Subject + will have to + base verb

2 Need To Expressions
Instructions :

Complete the necessity expressions with "need to" in appropriate tenses.

Step 1: "You ___ study harder" (need to)

Present necessity → Use "need to"

Complete: "You need to study harder"

Step 2: "She ___ prepare for the exam" (needs to)

Present necessity (3rd person) → Use "needs to"

Complete: "She needs to prepare for the exam"

Step 3: "Yesterday, I ___ buy groceries" (needed to)

Past necessity → Use "needed to"

Complete: "Yesterday, I needed to buy groceries"

Step 4: "Tomorrow, we ___ submit the report" (will need to)

Future necessity → Use "will need to"

Complete: "Tomorrow, we will need to submit the report"

Step 5: "He ___ improve his grades" (needs to)

Present necessity (3rd person) → Use "needs to"

Complete: "He needs to improve his grades"

Answers :

1. need to, 2. needs to, 3. needed to, 4. will need to, 5. needs to

Need To Rules :

• Present: I/You/We/They + need to + base verb

• Present: He/She/It + needs to + base verb

• Past: Subject + needed to + base verb

3 Be Able To Expressions
Instructions :

Complete the ability expressions with "be able to" in appropriate forms.

Step 1: "I ___ speak two languages" (am able to)

Present ability → Use "am able to"

Complete: "I am able to speak two languages"

Step 2: "She ___ swim across the pool" (is able to)

Present ability (3rd person) → Use "is able to"

Complete: "She is able to swim across the pool"

Step 3: "Yesterday, we ___ solve the problem" (were able to)

Past success → Use "were able to"

Complete: "Yesterday, we were able to solve the problem"

Step 4: "Tomorrow, they ___ finish the work" (will be able to)

Future ability → Use "will be able to"

Complete: "Tomorrow, they will be able to finish the work"

Step 5: "He ___ not participate due to illness" (was not able to)

Past inability → Use "was not able to"

Complete: "He was not able to participate due to illness"

Answers :

1. am able to, 2. is able to, 3. were able to, 4. will be able to, 5. was not able to

Be Able To Rules :

• Present: am/is/are + able to + base verb

• Past: was/were + able to + base verb

• Future: will be + able to + base verb

Advanced Semi-modal Exercises
4 Comparison Exercises
Instructions :

Compare semi-modals with true modals and choose the appropriate form.

Step 1: "He ___ work late tonight" (has to vs must)

External obligation (company policy) → Use "has to"

Complete: "He has to work late tonight"

Step 2: "She ___ finish the project" (must vs needs to)

Speaker's strong opinion → Use "must"

Complete: "She must finish the project"

Step 3: "I ___ swim well when I was young" (could vs was able to)

Specific past ability → Use "was able to"

Complete: "I was able to swim well when I was young"

Step 4: "You ___ not smoke here" (don't have to vs mustn't)

Prohibition → Use "mustn't"

Complete: "You mustn't smoke here"

Step 5: "They ___ improve their performance" (need to vs should)

Necessity vs advice → Use "need to"

Complete: "They need to improve their performance"

Answers :

1. has to, 2. must, 3. was able to, 4. mustn't, 5. need to

Comparison Rules :

• Have to: External obligation, Must: Internal obligation

• Be able to: All tenses available, Can: Limited tenses

• Need to: Necessity, Should: Advice

5 Modal Perfect with Semi-modals
Instructions :

Complete the modal perfect constructions with semi-modals.

Step 1: "She ___ have studied harder" (should have vs needed to have)

Past regret → Use "should have"

Complete: "She should have studied harder"

Step 2: "You ___ have told me earlier" (could have vs were able to have)

Past possibility → Use "could have"

Complete: "You could have told me earlier"

Step 3: "He ___ have passed the exam" (must have vs had to have)

Past logical deduction → Use "must have"

Complete: "He must have passed the exam"

Step 4: "They ___ have prepared better" (ought to have vs needed to have)

Past obligation → Use "ought to have"

Complete: "They ought to have prepared better"

Step 5: "We ___ have finished on time" (were able to vs managed to)

Past success → Use "were able to"

Complete: "We were able to finish on time"

Answers :

1. should, 2. could, 3. must, 4. ought to, 5. were able to

Modal Perfect Rules :

• Should have: Past regret or expectation

• Could have: Past possibility

• Must have: Past logical deduction

Key Points Summary
🎯
Semi-modal Structure: Semi-modals use "to" before the main verb (unlike true modals)
🔍
Have to vs Must: Have to = external obligation, Must = internal obligation
⚡
Be Able To: More flexible than "can" as it works in all tenses
📋
Need to: Expresses necessity, stronger than "should" but weaker than "must"
Have to
external obligation
Present/Past/Future
Need to
necessity
Present/Past/Future
Be able to
ability
All tenses
Semi-modals (have to, need to, be able to) Modal Auxiliaries and Semi-modals