Mustn’t vs. Don’t have to – English Grammar Exercises for B1
Choose the best option (A, B, C, or D) to complete each sentence. Read the text carefully, as all questions are part of a continuous note left by an older sibling for their younger sister.
Hey sis, I am heading out for work. Please read this note carefully!
1 I already washed all the dishes after lunch, so you ______ do them tonight.
(a) mustn’t
(b) don’t have to
(c) haven’t to
(d) shouldn’t
2 However, you ______ leave the front door unlocked when you go to bed!
(a) don’t have to
(b) mustn’t to
(c) mustn’t
(d) aren’t have to
3 I bought plenty of food on my way home, meaning you ______ cook anything for dinner.
(a) don’t have to
(b) mustn’t
(c) don’t need
(d) couldn’t
4 Mom called earlier and warned that we ______ touch the broken microwave under any circumstances.
(a) don’t have to
(b) mustn’t
(c) don’t must
(d) needn’t
5 The living room floor is completely clean, so you ______ sweep it today.
(a) haven’t to
(b) shouldn’t
(c) don’t have to
(d) mustn’t
6 I folded your laundry for you. You ______ put it in the closet right now if you are too tired.
(a) mustn’t
(b) don’t have to
(c) not have to
(d) shouldn’t
7 But please remember, you absolutely ______ leave your wet towels on the wooden floor!
(a) mustn’t
(b) don’t have to
(c) don’t must
(d) needn’t
8 It is Saturday tomorrow, so we ______ wake up early for school. Enjoy your sleep!
(a) don’t have to
(b) mustn’t
(c) haven’t to
(d) aren’t to
9 Since Dad just fixed the television, you ______ mess with the cables behind it.
(a) don’t have to
(b) mustn’t to
(c) mustn’t
(d) couldn’t
10 You ______ water the garden plants this afternoon because it rained heavily this morning.
(a) mustn’t
(b) haven’t to water
(c) don’t have to
(d) shouldn’t
11 I trust you, but you ______ let any strangers into the house while I am at work.
(a) don’t have to
(b) mustn’t
(c) don’t need
(d) haven’t
12 I took out all the trash bags, so you ______ worry about that bad smell anymore.
(a) don’t have to
(b) mustn’t
(c) don’t have
(d) wouldn’t
13 You can order pizza if you want, but you ______ use my credit card without asking!
(a) don’t have to
(b) shouldn’t
(c) mustn’t
(d) haven’t to
14 We have plenty of snacks in the fridge, so you ______ go to the convenience store tonight.
(a) don’t have to
(b) mustn’t
(c) don’t need
(d) cannot
15 You ______ finish all your homework tonight; you can easily do the rest on Sunday.
(a) mustn’t
(b) don’t have to
(c) not have to
(d) needn’t to
16 The new bathroom cleaner is highly toxic, so you ______ mix it with bleach!
(a) mustn’t
(b) don’t have to
(c) mustn’t mixing
(d) shouldn’t
17 As long as your room is tidy by the end of the week, you ______ clean it today.
(a) haven’t to
(b) mustn’t
(c) don’t have to
(d) couldn’t
18 I painted the hallway wall this morning. You ______ touch it until it is completely dry.
(a) mustn’t
(b) don’t have to
(c) don’t must
(d) shouldn’t
19 You can sleep early; you ______ wait up for me to come home from my night shift.
(a) mustn’t
(b) shouldn’t
(c) don’t have to
(d) aren’t have to
20 Ultimately, you can relax tonight, but you ______ forget to set the security alarm before bed.
(a) don’t have to
(b) mustn’t
(c) needn’t
(d) don’t must
ANSWER KEY & EXPLANATIONS
1 (b) don’t have to
- Why it is correct: The older sibling has done the chore, removing the obligation for the younger sister. It is not necessary.
- Distractor Analysis: (a) “mustn’t” is a Common Mistake (it means she is forbidden from washing dishes). (c) “haven’t to” is a Structural Error. (d) “shouldn’t” is a Meaning Trap.
2 (c) mustn’t
- Why it is correct: Leaving the door unlocked is a major security risk. It is strictly forbidden.
- Distractor Analysis: (a) “don’t have to” is a Common Mistake (implies she can leave it unlocked if she wants, which is dangerous). (b) “mustn’t to” is a Structural Error (no “to” after modals). (d) “aren’t have to” is a Structural Error.
3 (a) don’t have to
- Why it is correct: Food is already bought, so the act of cooking is unnecessary (lack of obligation).
- Distractor Analysis: (b) “mustn’t” is a Common Mistake. (c) “don’t need” is a Structural Error (requires “to” -> “don’t need to”). (d) “couldn’t” is a Meaning Trap.
4 (b) mustn’t
- Why it is correct: Touching a broken electrical appliance is dangerous. It is a strict prohibition.
- Distractor Analysis: (a) “don’t have to” is a Common Mistake. (c) “don’t must” is a Structural Error. (d) “needn’t” is a Meaning Trap (means “lack of necessity,” not prohibition).
5 (c) don’t have to
- Why it is correct: The floor is clean, so sweeping is an unnecessary action.
- Distractor Analysis: (d) “mustn’t” is a Common Mistake. (a) “haven’t to” is a Structural Error. (b) “shouldn’t” is a Meaning Trap.
6 (b) don’t have to
- Why it is correct: Putting the clothes away immediately is not required; she has the choice to rest instead.
- Distractor Analysis: (a) “mustn’t” is a Common Mistake. (c) “not have to” is a Structural Error. (d) “shouldn’t” is a Meaning Trap.
7 (a) mustn’t
- Why it is correct: Wet towels ruin wooden floors. It is a strict house rule not to do this.
- Distractor Analysis: (b) “don’t have to” is a Common Mistake. (c) “don’t must” is a Structural Error. (d) “needn’t” is a Meaning Trap.
8 (a) don’t have to
- Why it is correct: Because it is the weekend, the obligation to wake up early is removed.
- Distractor Analysis: (b) “mustn’t” is a Common Mistake. (c) “haven’t to” is a Structural Error. (d) “aren’t to” is a Structural Error.
9 (c) mustn’t
- Why it is correct: Messing with the cables could break the TV again. It is a strict warning.
- Distractor Analysis: (a) “don’t have to” is a Common Mistake. (b) “mustn’t to” is a Structural Error. (d) “couldn’t” is a Meaning Trap.
10 (c) don’t have to
- Why it is correct: Nature already watered the plants (rain), so she is free from this chore.
- Distractor Analysis: (a) “mustn’t” is a Common Mistake. (b) “haven’t to water” is a Structural Error. (d) “shouldn’t” is a Meaning Trap.
11 (b) mustn’t
- Why it is correct: Letting strangers in is a severe safety hazard. It is entirely prohibited.
- Distractor Analysis: (a) “don’t have to” is a Common Mistake (means “you don’t need to let them in, but you can if you want,” which is completely wrong here). (c) “don’t need” is a Structural Error. (d) “haven’t” is a Structural Error.
12 (a) don’t have to
- Why it is correct: The older sibling solved the problem, so the sister is freed from worrying about it.
- Distractor Analysis: (b) “mustn’t” is a Common Mistake. (c) “don’t have” is a Structural Error (missing “to”). (d) “wouldn’t” is a Meaning Trap.
13 (c) mustn’t
- Why it is correct: Using someone else’s credit card without permission is forbidden.
- Distractor Analysis: (a) “don’t have to” is a Common Mistake. (b) “shouldn’t” is a Meaning Trap (too weak for stealing/using a card without permission). (d) “haven’t to” is a Structural Error.
14 (a) don’t have to
- Why it is correct: Since they have food, leaving the house is unnecessary.
- Distractor Analysis: (b) “mustn’t” is a Common Mistake. (c) “don’t need” is a Structural Error (needs “to”). (d) “cannot” is a Meaning Trap.
15 (b) don’t have to
- Why it is correct: She is allowed to finish her homework tonight if she wants to, but it is not obligatory.
- Distractor Analysis: (a) “mustn’t” is a Common Mistake. (c) “not have to” is a Structural Error. (d) “needn’t to” is a Structural Error.
16 (a) mustn’t
- Why it is correct: Mixing chemicals can create poison gas. This is a life-saving prohibition.
- Distractor Analysis: (b) “don’t have to” is a Common Mistake. (c) “mustn’t mixing” is a Structural Error (requires bare infinitive). (d) “shouldn’t” is a Meaning Trap (too weak for a toxic warning).
17 (c) don’t have to
- Why it is correct: She has a flexible deadline (the end of the week), meaning she is not required to do it today.
- Distractor Analysis: (a) “haven’t to” is a Structural Error. (b) “mustn’t” is a Common Mistake. (d) “couldn’t” is a Meaning Trap.
18 (a) mustn’t
- Why it is correct: Touching wet paint will ruin the wall. It is an absolute rule not to touch it.
- Distractor Analysis: (b) “don’t have to” is a Common Mistake. (c) “don’t must” is a Structural Error. (d) “shouldn’t” is a Meaning Trap.
19 (c) don’t have to
- Why it is correct: Waiting up is an obligation she is freed from; she can comfortably go to sleep.
- Distractor Analysis: (a) “mustn’t” is a Common Mistake. (b) “shouldn’t” is a Meaning Trap. (d) “aren’t have to” is a Structural Error.
20 (b) mustn’t
- Why it is correct: Forgetting to set the alarm leaves the house unprotected. It is a critical safety rule.
- Distractor Analysis: (a) “don’t have to” is a Common Mistake (means “you can forget if you want to,” which defeats the purpose of an alarm). (c) “needn’t” is a Meaning Trap. (d) “don’t must” is a Structural Error.
GRAMMAR POINTS TO REMEMBER
1 DON’T HAVE TO (The Relief of No Obligation):
- Meaning: It is NOT necessary. I have done the work, or the situation has changed, so you are free to rest. You can still do the action if you really want to, but there is zero pressure.
- Context (Chores): You don’t have to cook (because I bought pizza). You don’t have to sweep the floor (because it is already clean).
2 MUSTN’T (The Strict Safety Boundary):
- Meaning: Do NOT do this. It is highly dangerous, breaks the rules, or will ruin something. You have absolutely no choice in the matter.
- Context (Safety): You mustn’t leave the door unlocked. You mustn’t mix dangerous chemicals. You mustn’t touch wet paint.
The Sibling Rule: If doing the action is lazy but harmless, use don’t have to. If doing the action is dangerous or causes a disaster, use mustn’t!