logo
logoGrammar Error
Test Your EnglishLearnChallengesArticlesAbout
logoGrammar Error

Must vs. Have To: Expressing Obligation: correct answers

StartTo ChallengesDownload PDF
Jump to answers ↓

Basics: Must and Have To - Obligation

This challenge contains 12 questions at easy difficulty covering Basics: Must and Have To - Obligation. Test your knowledge with a mix of question formats!

Try the quiz to check your knowledge!

EasyA2 | Elementary | Pre-intermediateA2Modal verbQuestionsNegationEnglish Grammar Basics

Correct answers

Question 1

Complete the stressed student's morning reminders by choosing the correct word for each blank.

I must remember to buy coffee before my morning lecture. The syllabus says that everyone has to complete the online quiz before class begins.

I must remember to buy coffee before my morning lecture.

The modal verb must is followed directly by a base verb (like remember). If we wanted to use have, we would need to include "to" (I have to remember).

The syllabus says that everyone has to complete the online quiz before class begins.

The pronoun "everyone" is singular, so it requires the singular verb form has to. "Have to" is plural, and "musts" is not a real word (modal verbs never take an -s ending!).

Question 2

Help the dramatic knight understand his king's orders by choosing the correct phrase.

"You ___ the dragon before sunset, or we won't have a fire to roast our royal marshmallows!"

The correct answer is must defeat.

The modal verb "must" is always followed directly by a bare infinitive (the base form of the verb without "to"). "Must to defeat" and "must defeating" are grammatically incorrect.

Question 3

Complete the exhausted roommate's diary entry about living with a fitness fanatic by selecting the best verbs.
"My roommate is completely obsessed with his morning routine. He _________________________ wake up at 5:00 AM every single day to run. I, on the other hand, _________________________ wake up until 8:00 AM, thank goodness!"

The correct answers are has to and don't have to.

When using "have to" for external obligations or routines, the verb changes to match the subject. For the third-person singular ("he"), we use has to.

Note: "Must" never takes "to" after it, making "must to" grammatically incorrect.

Question 4

You are reading a top-secret manual for surviving a vampire attack. Select ALL the grammatically correct options to complete this crucial safety rule.
"If you hear a knock at your window at midnight, you ________ keep the door locked!"

The correct answers are must, have to, and have got to.

All three of these options correctly express strong obligation or necessity for the pronoun "you".

Have got to is a slightly more informal (but perfectly correct) way to say have to.

"Must to" is incorrect because modal verbs are followed by a bare infinitive (no "to"). "Has to" is incorrect because it is only used for third-person singular subjects (he/she/it).

Question 5

Select the grammatically correct question for this grumpy teenager.

"___ wear this extremely itchy sweater to Aunt Martha's party?"

The correct answer is Do I have to.

When asking a question about an obligation with "have to", we use the auxiliary verb "do" or "does" (e.g., "Do I have to?"). "Must" can be used in questions without "do" (e.g., "Must I wear...?"), but we never say "Do I must" or "Must I to".

Question 6

Review Professor Higgins' famously terrifying class syllabus. Select ALL the phrases that correctly complete his rule about classroom supplies.
"To pass this class, each student ________ bring a perfectly sharpened pencil to every lecture."

The correct answers are must and has to.

"Each student" is a singular subject (he/she/they).

We use the singular form has to instead of "have to".

Must is a modal verb, which means its form never changes regardless of the subject (so "musts" is not a real word!). Both correct options express a strong obligation or rule.

Question 7

Help the unlucky driver finish his text message to his friend by choosing the correct verb for each blank.

Yesterday, my car broke down in the rain, so I had to walk three miles to work! At least I didn't have to pay for parking.

Yesterday, my car broke down in the rain, so I had to walk three miles to work!

Because this happened "yesterday," we need a past tense verb. The modal must does not have a past tense form, so we always use had to for obligations in the past.

At least I didn't have to pay for parking.

To express a lack of obligation in the past (something that wasn't necessary), we use didn't have to. "Must not" cannot be used for the past tense.

Question 8

Help the frantic baking instructor remind her students of the kitchen rules by choosing the correct phrase for each blank.
"Listen up, everyone! You _________________________ eat the raw eggs, unless you want a trip to the hospital! However, you _________________________ frost the cupcakes right this second—take your time and do it when they finally cool down."

The correct answers are mustn't and don't have to.

We use mustn't (must not) to express a strict prohibition—something you are absolutely not allowed to do.

We use don't have to to show a lack of obligation—meaning you can do it if you want, but it is not required.

Question 9

Complete the student's dramatic text message explaining why he missed the morning lecture. Select the correct option for each gap.
"I'm so sorry I'm late! I _________________________ rescue a very angry raccoon from my garbage can this morning. Because of that little adventure, I missed the bus and _________________________ walk three miles in the pouring rain!"

The correct answers are had to and had to.

The modal verb "must" does not have a past tense form. To talk about an obligation or necessity in the past, we always use had to.

Question 10

Complete the frustrated college student's text message to their mom.

"It's so unfair! My roommate never cleans, so our poor robot vacuum ___ do all the work."

The correct answer is has to.

Because "our poor robot vacuum" is a third-person singular subject (it), we must use "has to" instead of "have to" to express obligation. "Must to" is always incorrect because "must" never takes "to".

Question 11

Help the new gym member understand the rules by choosing the correct phrase for each blank.

You must not wear outdoor shoes on the basketball court, because the dirt will ruin the wood. However, you don't have to bring your own towel, because the front desk provides them for free.

You must not wear outdoor shoes on the basketball court, because the dirt will ruin the wood.

We use must not (or mustn't) for strict prohibitions—things you are absolutely not allowed to do. "Doesn't have to" is grammatically incorrect for the pronoun "you".

However, you don't have to bring your own towel, because the front desk provides them for free.

We use don't have to when there is no obligation. It means bringing a towel is not necessary, but you can if you really want to!

Question 12

Help the exhausted college student leave a polite but firm note for their extremely messy roommate. Select ALL the grammatically correct sentences that express a strong obligation.

The correct answers are You must wash... and You have to wash...

Both must and have to are used to express strong obligation in the present tense.

"Must" is a modal verb and is never followed by "to" (so "must to" is incorrect).

"Have to" changes to "has to" only for third-person singular subjects (he/she/it), so "you has to" is incorrect.

Terms of ServicePrivacy Policy
Copyright Kind Robots Ltd.