1. Obligation and Necessity:
- Must (mustn’t): Indicates a strong obligation or necessity. You must complete your homework.
- Have to: Implies an obligation, often due to external factors. You have to attend the meeting.
- Have got to: Similar to “have to,” more common in spoken English. I’ve got to finish this report.
- Need to: Indicates necessity, often used in both spoken and written English. You need to book your tickets in advance.
2. No Obligation:
- Not have to/Don’t have to: Denotes the absence of obligation. You don’t have to attend the event.
- Not need to/Don’t need to: Indicates lack of necessity. You don’t need to bring your own laptop.
3. Lack of Obligation in the Past:
- Didn’t need to: Expresses that something was not necessary in the past. I didn’t need to study last night.
- Needn’t have + past participle: Suggests something was unnecessary but still done. I needn’t have bought so much food.
4. Suggestions and Advice:
- Should (shouldn’t): Gives advice or suggestions. You should study more for the exam.
- Ought to (ought not to): Similar to “should,” emphasizes moral obligation. You ought to apologize for your mistake.
- Must: Used to give strong advice. You must follow the safety guidelines.
5. Adverbs:
- Adverbs like also, always, never, sometimes, just, and only come after modal verbs. You must always wear your seatbelt.
- To add emphasis, use “really” before the verb. You really must attend the seminar.
6. Formal Written English:
- Verbs of obligation, necessity, and suggestion are common in formal and academic writing to express opinions. Businesses need to prioritize customer satisfaction.
Modal verbs and related expressions are used to convey a range of meanings related to obligation, necessity, advice, and suggestions in both spoken and written English.