Modals of Obligation (Must, Have to, Should) – English Grammar Exercises for A2
You are traveling and visiting various places like airports, construction sites, and hospitals. You see many safety signs and are explaining these strict rules to your friends. Read the notices and conversations carefully, then choose the best option (A, B, C, or D) to complete each sentence.
1 “Attention passengers: You ______ fasten your seatbelt while the seatbelt sign is illuminated.”
(A) must to
(B) must
(C) should
(D) have
2 “Look at that warning sign on the fence. It says everyone ______ wear a hard hat before entering the construction site.”
(A) should
(B) musts
(C) must
(D) having to
3 “Danger! High Voltage. You ______ touch these electrical wires.”
(A) don’t have to
(B) shouldn’t
(C) mustn’t
(D) haven’t to
4 “The sign in the airplane bathroom says: You ______ smoke on this flight. It is a strict federal law.”
(A) shouldn’t
(B) don’t have to
(C) mustn’t
(D) not must
5 “Emergency Exit: You ______ leave bags or boxes in front of this door at any time.”
(A) mustn’t
(B) don’t have to
(C) shouldn’t to
(D) aren’t have to
6 “Look at the red flag on the beach. It means we ______ swim here today because the waves are deadly.”
(A) shouldn’t
(B) don’t have to
(C) mustn’t
(D) not must
7 “The notice at the zoo is very clear: Visitors ______ feed the animals. It makes them sick.”
(A) don’t have to
(B) mustn’t
(C) shouldn’t
(D) haven’t to
8 “Quiet Zone: You ______ turn off your mobile phones before entering the hospital building.”
(A) must
(B) must to
(C) should
(D) have
9 “Safety Notice: All laboratory workers ______ wash their hands after handling dangerous chemicals.”
(A) have
(B) should to
(C) must
(D) musts
10 “Friend: Do we really need to wear these ugly safety glasses?”
“You: Yes, the sign says everyone ______ wear them in this area. It’s a strict rule.”
(A) musts
(B) must
(C) should to
(D) have
11 “Warning: You ______ drive faster than 20 km/h in this school zone. There are cameras everywhere.”
(A) shouldn’t
(B) mustn’t
(C) don’t have to
(D) haven’t to
12 “Notice: Passengers ______ put all heavy bags under the seat in front of them during takeoff and landing.”
(A) must
(B) must to
(C) should
(D) are must
13 “Fire Safety Door: You ______ keep this door closed at all times to prevent fires from spreading.”
(A) should
(B) have
(C) must
(D) must to
14 “At the gas station, the sign says you ______ turn off your car engine before you pump gas. It is highly dangerous otherwise.”
(A) must
(B) should to
(C) having to
(D) have
15 “Danger: Deep Water. Children ______ play near the edge of the pool without an adult present.”
(A) don’t have to
(B) mustn’t
(C) shouldn’t
(D) haven’t to
16 “Airport Security Notice: You ______ leave your luggage unattended. Abandoned bags will be destroyed.”
(A) shouldn’t
(B) don’t have to
(C) mustn’t
(D) not must
17 “Look at the yellow line on the train platform. The sign says we ______ stand behind it until the train stops.”
(A) should
(B) must
(C) must to
(D) have
18 “You ______ take photos in this part of the museum. Look at the ‘No Cameras’ sign right there!”
(A) don’t have to
(B) mustn’t
(C) shouldn’t to
(D) haven’t to
19 “Attention: All visitors ______ sign their names in the security book at the front desk before going upstairs.”
(A) must
(B) musts
(C) should to
(D) have
20 “Friend: Can I take off my seatbelt now?”
“You: No, the sign is still red. You ______ stay in your seat until it turns off.”
(A) should
(B) have
(C) must
(D) must to
ANSWER KEY & EXPLANATIONS
1 Key: (B) must
Explanation: Public signs and official safety notices almost always use “must” to declare a strict, mandatory rule. “Should” is too weak, and “must to” is grammatically incorrect.
2 Key: (C) must
Explanation: A hard hat rule at a construction site is a strict safety law. Modals do not take an “s”, so “musts” is invalid.
3 Key: (C) mustn’t
Explanation: “Mustn’t” is used for strict prohibitions. Touching high voltage is deadly, making it absolutely forbidden.
4 Key: (C) mustn’t
Explanation: Federal laws use “mustn’t” to declare something illegal. “Don’t have to” means you are allowed to do it if you want, which is completely wrong here.
5 Key: (A) mustn’t
Explanation: Blocking an emergency exit is illegal and dangerous. “Mustn’t” expresses this strict prohibition.
6 Key: (C) mustn’t
Explanation: A red flag on a beach signifies deadly conditions. “Mustn’t” shows it is forbidden to swim. “Shouldn’t” is too soft for a life-or-death warning.
7 Key: (B) mustn’t
Explanation: Zoo rules are strict prohibitions to protect the animals.
8 Key: (A) must
Explanation: A strict hospital rule. “Must to” is always incorrect.
9 Key: (C) must
Explanation: A formal safety notice in a laboratory.
10 Key: (B) must
Explanation: Reading a direct safety rule. “Everyone” is the subject, but modals like “must” never change form or take an “s”.
11 Key: (B) mustn’t
Explanation: A strict speed limit enforced by cameras. “Don’t have to” would mean it’s optional, which is incorrect.
12 Key: (A) must
Explanation: An official airplane safety regulation.
13 Key: (C) must
Explanation: Fire safety rules use “must” to show absolute necessity.
14 Key: (A) must
Explanation: A strict, dangerous rule at a gas station.
15 Key: (B) mustn’t
Explanation: A strict safety rule for children. “Don’t have to” would mean the children don’t need to play there, but they are allowed to—which is dangerously wrong!
16 Key: (C) mustn’t
Explanation: A strict airport security law. “Unattended” means left alone.
17 Key: (B) must
Explanation: A strict public transport safety rule.
18 Key: (B) mustn’t
Explanation: Explaining a “No Cameras” sign. The sign creates a strict prohibition.
19 Key: (A) must
Explanation: A formal security rule for entering a building.
20 Key: (C) must
Explanation: The illuminated sign dictates a strict rule that cannot be broken until it is turned off.
GRAMMAR POINTS TO REMEMBER
1 “Must” for Public Notices and Signs:
- In everyday conversation, native speakers often use “have to” to talk about rules. However, on official written signs, formal notices, and safety warnings, the word MUST is almost exclusively used.
- Example: “Passengers must fasten their seatbelts.” (Official airline rule).
- Example: “Hard hats must be worn.” (Construction site rule).
2 “Mustn’t” (Prohibition):
- We use mustn’t (must not) to say that something is strictly forbidden, illegal, or highly dangerous. It is the strongest way to say “NO”.
- Example: “You mustn’t touch the art.” (It is forbidden).
3 Mustn’t vs. Don’t have to (The Danger Trap!):
- Mustn’t = Do not do this. It is bad/illegal. (You mustn’t swim here. = You will drown).
- Don’t have to = You have a choice. It is not required. (You don’t have to swim here. = You can swim if you want, or you can stay on the sand).
- Never mix these up on a safety test!
4 The Grammar Rules for Modals:
- Never put “to” after must or should. (Say: You must stop. NOT: You must to stop.)
- Modals never take an “-s” for he/she/it/everyone. (Say: Everyone must go. NOT: Everyone musts go.)