Tense, Aspect & Modal Verbs: Rules, Uses & NEB Exam Tricks

TAKEAWAYS:

• Master the 12 verb tenses (simple, continuous, perfect, perfect continuous) and their time signals (yesterday, now, since, for, etc.).
• Understand aspect (progressive vs. perfective) to avoid common mistakes like "I am knowing" (wrong) vs. "I have known" (correct).
• Learn modal verbs (can/could, may/might, must, should) for ability, permission, advice, and deduction.
• Practice time shifts (e.g., direct vs. indirect speech) and sequence of tenses in reported speech.
• Spot NEB exam traps like mixed tenses, incorrect modals, and aspect errors in sentences.
• Use signal words (e.g., already, yet, still, for/since) to identify the correct tense.

1. What Are Tenses?

Tenses show when an action happens. English has 12 tenses, divided into 4 main types based on time (past, present, future) and aspect (simple, continuous, perfect, perfect continuous).

1.1 The 4 Aspects

1.2 The 3 Main Time Frames

• Present (now/habit)
• Past (before now)
• Future (after now)

Example:

• Present Simple: "I work in Kathmandu." (habit)
• Past Continuous: "I was working when you called." (interrupted action)
• Future Perfect: "By 2025, I will have graduated." (completed future action)

2. The 12 Tenses (With Rules & Examples)

2.1 Present Tenses

Signal Words:

• Present Simple: always, usually, every day
• Present Continuous: now, at the moment
• Present Perfect: already, yet, just, since, for
• Present Perfect Continuous: for, since, all day

Example Sentences:

1. She works in a school. (habit)
2. She is working on a project. (now)
3. She has worked here for 5 years. (past → present)
4. She has been working hard lately. (ongoing effort)

2.2 Past Tenses

Signal Words:

• Past Simple: yesterday, last week, in 2010
• Past Continuous: while, when
• Past Perfect: before, after, by the time
• Past Perfect Continuous: for, since (with past time)

Example Sentences:

1. She taught English last year. (completed)
2. She was teaching when the earthquake struck. (interrupted)
3. She had taught for 10 years before she moved. (before another past action)
4. She had been teaching for 5 years when she got promoted. (duration)

2.3 Future Tenses

Signal Words:

• Future Simple: tomorrow, next week, in 2025
• Future Continuous: at 5 PM, this time tomorrow
• Future Perfect: by next year, by the time
• Future Perfect Continuous: for 10 years by 2030

Example Sentences:

1. She will teach tomorrow. (simple future)
2. She will be teaching at 2 PM. (future continuous)
3. By 2025, she will have taught for 15 years. (future perfect)
4. By 2030, she will have been teaching for 20 years. (future perfect continuous)

3. Common Mistakes & How to Avoid Them

❌ Wrong: "I am knowing English." ✅ Correct: "I know English." (Present Simple for facts) ❌ Wrong: "She has went to school." ✅ Correct: "She has gone to school." (Past Participle of go is gone, not went)

❌ Wrong: "I will have been going to school for 10 years next year." ✅ Correct: "I will have been at school for 10 years next year." (Future Perfect Continuous)

4. Aspect vs. Tense (Key Difference)

Example Trace:

• "She writes books." (Simple Present → habit)
• "She is writing a book." (Present Continuous → now)
• "She has written 5 books." (Present Perfect → past result)
• "She has been writing for 5 years." (Present Perfect Continuous → ongoing duration)

5. Modal Verbs (Can, Could, May, Might, Must, Should, etc.)

Modals express ability, permission, advice, possibility, or necessity.

classDiagram
    class ModalVerb {
        +ability()
        +permission()
        +advice()
        +deduction()
    }
    class Can {
        +can + base verb
        +‘ability’: *She **can swim**.*
        +‘permission’: *You **can** leave now.*
    }
    class Must {
        +must + base verb
        +‘obligation’: *You **must** submit the report.*
        +‘deduction’: *She **must be** tired.*
    }
    class Should {
        +should + base verb
        +‘advice’: *You **should** study harder.*
        +‘probability’: *She **should have** arrived by now.*
    }
    ModalVerb <|-- Can
    ModalVerb <|-- Must
    ModalVerb <|-- Should
    note for ModalVerb
        **Signal Words:**
        - *Can/Could*: ‘be able to’
        - *May/Might*: ‘perhaps’
        - *Must*: ‘have to’
        - *Should*: ‘ought to’
    end note

5.1 Common Modals & Their Uses

Example Sentences:

1. She can speak five languages. (ability)
2. She could not attend the meeting. (past inability)
3. May I borrow your pen? (permission)
4. She might be at home. (possibility)
5. You must submit the assignment on time. (necessity)
6. You should visit your grandparents. (advice)

5.2 Modal + Perfect (For Past Actions)

Example Sentences:

1. She must have finished her homework. (I see it done)
2. She could have won the match. (but lost)
3. She should have arrived by now. (but she’s late)
4. She might have taken the wrong bus. (unlikely)

6. Time Shifts in Reported Speech

When reporting what someone said, tenses change based on the original and reported time.

Example:

• Direct: "I go to school every day."
• Reported: She said she went to school every day.

Exception: If the statement is still true, the tense does not change.

• Direct: "The Earth is round."
• Reported: She said the Earth is round.

7. NEB Exam Tips

7.1 Common NEB Question Types

1. Fill in the blanks (choose the correct tense/modal)
   • She _____ (write) a letter yesterday. → had written
2. Correct the errors (identify tense/modal mistakes)
   • He is knowing the answer. → knows (Simple Present)
3. Rewrite sentences (change direct to reported speech)
   • She said, "I am happy." → She said she was happy.
4. Complete the table (match tenses to signals)
5. Answer in full sentences (use correct tenses/modals)

7.2 How to Score Full Marks

✅ Read carefully – Check if the sentence is about habit, completion, progress, or future. ✅ Spot signal words – since, for, already, yet, tomorrow, last week. ✅ Avoid mixing tenses – Don’t write "I am going to school yesterday." ✅ Use modals correctly –

• Can = ability (She can swim.)
• Could = past ability (She could swim when young.)
• Must = necessity (You must submit on time.) ✅ Practice reported speech – Remember: backshift tenses (Present → Past, Past → Past Perfect).

8. Solved NEB-Style Examples

Example 1: Fill in the Blanks (Tense)

She _____ (live) in Kathmandu since 2010.

• Answer: has been living (Present Perfect Continuous – action started in the past and continues)

Example 2: Correct the Error (Modal)

He can to swim.

• Answer: He can swim. (No "to" after can)

Example 3: Rewrite in Reported Speech

She said, "I will call you tomorrow."

• Answer: She said she would call me the next day.

Example 4: Choose the Correct Option

By next year, she _____ (teach) for 20 years. A) will teach B) will have been teaching C) teaches D) has taught

• Answer: B) will have been teaching (Future Perfect Continuous)

9. Practice Questions (NEB Style)

Section A: Fill in the Blanks

1. She _____ (write) a book last year. (Past Simple)
2. They _____ (live) here since 2005. (Present Perfect Continuous)
3. By 2025, I _____ (complete) my degree. (Future Perfect)
4. She _____ (not finish) her homework yet. (Present Perfect)
5. _____ I borrow your pen? (May + base verb)

Section B: Correct the Errors

1. He is knowing the answer. → _______________
2. She has went to school. → _______________
3. I will have been going to the party tomorrow. → _______________
4. She can to swim. → _______________
5. They must have went to the market. → _______________

Section C: Rewrite in Reported Speech

1. He said, "I am happy."
2. She said, "I have finished my work."
3. They said, "We will visit you next week."

Section D: Choose the Correct Option

1. She _____ (teach) English for 10 years. A) is teaching B) has been teaching C) teaches D) was teaching

2. By next month, they _____ (complete) the project. A) will complete B) will have completed C) complete D) have completed

10. Answers to Practice Questions

Section A:

1. wrote
2. have been living
3. will have completed
4. has not finished
5. May

Section B:

1. He knows the answer.
2. She has gone to school.
3. I will have been at the party tomorrow.
4. She can swim.
5. They must have gone to the market.

Section C:

1. He said he was happy.
2. She said she had finished her work.
3. They said they would visit us the next week.

Section D:

1. B) has been teaching (Present Perfect Continuous)
2. B) will have completed (Future Perfect)

Final Exam Tip:

• Always check for signal words (since, for, yesterday, tomorrow).
• Modals are tricky – must = necessity, should = advice, could = past ability.
• Reported speech requires tense shifts – Present → Past, Past → Past Perfect.
• Practice daily – Write 5 sentences in each tense to master them.

Good luck for your NEB exam! 🚀