Printable Must Exercises - 101 PDF Worksheets with Answers

Must/Mustn't Printable PDF Worksheet Tests with Exercises and Answers

Access a collection of 101 printable PDF worksheets focusing on the English grammar topic of the must. Download fill-in-the-blank tests with exercises and answer keys for must/mustn't to print for free. The activities in the sheets are suitable for kids, adults, ESL learners at the beginner, elementary, and intermediate levels to practice English grammar.

Must: The Modal Auxiliary Verb of Strong Obligation and Necessity

The English language is enriched with various modal auxiliary verbs that serve to express different meanings and nuances. Among these, must stands out as a versatile and powerful modal verb that conveys a sense of strong obligation, necessity, duty, or moral responsibility. Let's delve deeper into the multifaceted nature of must and explore how it is used in different contexts to express various ideas with conviction and certainty.

Expressing Strong Obligation and Necessity

At its core, must is a modal verb that signifies strong obligations or requirements. When we use must in a sentence, we emphasize the importance of adhering to certain rules, regulations, or social norms. This helps to convey a sense of responsibility and duty. For instance:

"You must attend the meeting to discuss the new project plan."
"All employees must wear a uniform while on duty."
"Passengers must fasten their seat belts during the entire flight."

Implying Duty and Moral Obligation

Must goes beyond mere obligations; it also carries an element of moral responsibility. By using must in a sentence, we express a duty or ethical obligation to act in a certain way, often in consideration of others. For example:

"We must help those in need during times of crisis."
"As a responsible citizen, I must vote in every election."
"We must treat others with kindness and respect."

Conveying Firm Recommendations and Advice

Beyond obligations and moral duties, must can be employed to provide strong recommendations or advice. When using must in this context, we indicate that a particular action is highly beneficial, advisable, or even essential. For instance:

"You must try this restaurant; their food is outstanding."
"You must visit that museum; it houses an impressive art collection."
"In preparation for the exam, you must take this matter seriously and study diligently."

Indicating a High Level of Certainty

Must is not limited to expressing obligations and recommendations; it denotes a high level of certainty or confidence in the statement being made. When we use must in a sentence, we are essentially expressing a strong belief in the truth or accuracy of the statement. For example:

"The answer must be correct; I have thoroughly checked my calculations."
"He must know the answer; he is an expert in this field."
"Based on the evidence presented, she must be the new manager."

Emphasizing Essential Conditions and Prerequisites

In certain contexts, must is employed to emphasize essential conditions or prerequisites for specific outcomes or events. By using must in these cases, we highlight the necessity of fulfilling certain requirements to achieve a particular goal. For instance:

"To win the prize, you must be present at the awards ceremony."
"In order to secure the job, you must pass the qualifying test with a high score."
"We must stay focused and work diligently to succeed in our ambitious project."

Conveying Inevitable Consequences

In some instances, must is used to convey that a particular action will inevitably lead to a certain consequence or result. By using must in such cases, we underscore the inevitability of the outcome. For example:

"If you touch fire, you must get burned; it's a natural consequence."
"Change is constant; it must happen, and we must adapt to it."

Conveying Personal Determination and Resolve

Apart from expressing external obligations and consequences, must can also be used to convey a sense of personal determination, resolve, or commitment. By using must in this manner, we express our strong will to achieve a goal or overcome challenges. For instance:

"I must improve my skills to excel in my chosen profession."
"I must overcome my fears and take bold steps towards personal growth."
"As a team, we must find a solution to the problem and persevere until we succeed."

Mustn't: The Negative Form of Prohibition

On the flip side, the negative form of "must", "mustn't", is employed to indicate strict prohibition or a rule that must not be violated. By using "mustn't" in a sentence, we make it clear that certain actions are not allowed or are strictly prohibited. For example:

"You mustn't smoke here; smoking is strictly prohibited in this area."
"You mustn't handle the chemicals carelessly; they are hazardous."

Used in Formal and Official Contexts

Due to its authoritative and serious tone, must is often utilized in formal and official contexts, such as rules, regulations, guidelines, safety warnings, and legal documents. By using must in these contexts, we create an air of authority and reinforce the importance of compliance. For instance:

"Reports must be submitted by Friday, without exception."
"All applicants must be over 18 years old to qualify for this position."
"Customers must wear masks in the store as part of our safety protocols."

Used to Express Certainty and Deduction

In addition to indicating obligations and requirements, must is employed to express certainty based on evidence or logical deduction. By using must in this way, we draw conclusions with confidence. For example:

"Based on the tracking information, the package must have arrived at its destination."
"He must be at home by now because I saw his car parked outside."

Must in Academic and Educational Contexts

In academic and educational settings, must is frequently used to indicate compulsory assignments, readings, or activities that students are required to complete as part of their learning process. It serves as a directive for students to fulfill certain academic responsibilities.

Must in Negotiations and Business Discussions

Within negotiations and business discussions, must is employed to express certainty and insistence on particular terms, requirements, or agreements. Its use in these contexts emphasizes the non-negotiable nature of certain conditions.

Must in Expressing Unbreakable Rules and Natural Laws

In certain situations, must is used to assert unbreakable rules or laws of nature, where the outcome is inevitable and cannot be altered. This usage emphasizes the inescapable nature of certain events or phenomena.

Must in Safety Instructions and Emergency Situations

In safety instructions and emergency situations, must is commonly found in cautionary statements and warnings. Its use emphasizes the importance of adhering to safety guidelines for the protection of individuals and the prevention of accidents.

Must for Survival and Basic Necessities

Must can also be applied in contexts related to survival and basic necessities. In these cases, it conveys the essential actions or requirements that are indispensable for living or thriving.

Must for Expressing Responsibility and Accountability

In various situations, must is used to indicate a sense of responsibility or accountability for one's actions or decisions. This usage highlights the need to take ownership of the consequences of one's choices.

Must in Commanding and Asserting Authority

Must can be employed to make commands or assert authority in a strong and decisive manner. Its use in these instances leaves little room for negotiation or defiance.

Must in Expressing Expectations and Requirements

In both professional and personal contexts, must is utilized to indicate that certain actions, results, or behaviors are expected or required. This usage emphasizes the importance of meeting certain standards or expectations.

Must in Conveying Inevitability and Unavoidability

In certain contexts, must is employed to convey the idea that something is inevitable or unavoidable. It suggests that certain outcomes or consequences are bound to occur regardless of efforts to prevent them.

Must in Expressing Compulsion and Irresistible Influence

In some situations, must is used to express a sense of compulsion or irresistible influence over a person's decisions or actions. This usage emphasizes the compelling nature of a particular situation or event.


In conclusion, must is a remarkably versatile and powerful modal auxiliary verb that adds conviction and certainty to our expressions. Whether it is used to convey strong obligations, moral responsibilities, firm recommendations, or a high level of certainty, must plays a crucial role in both everyday conversations and formal settings. Its ability to underscore the importance of certain actions and decisions, along with its inherent sense of responsibility and determination, makes must a vital element of the English language. By mastering the diverse applications of "must", we can effectively communicate a wide range of ideas, from giving advice and expressing obligations to making strong recommendations and emphasizing essential conditions. Through its presence in various contexts, must enhances the clarity and impact of our communication, making it an indispensable tool in expressing conviction and necessity.