But for contrast

But is a coordinating conjunction. It joins units doing the same grammatical job: adjective with adjective, verb phrase with verb phrase, or one full clause with another.

A useful check is to identify the two parts and ask whether they can be compared at the same level. Quiet but friendly contrasts two qualities; works at home but studies at college contrasts two actions of one subject; I called, but Maya was busy joins two separate messages.

The parts do not need to be equally long. Their role and completeness matter, not their word count.

If both actions concern the same subject, it is usually not repeated: I like the colour but do not like the size. The subject I belongs to both verb phrases.

If the actors differ, name each one: I like mornings, but my partner prefers evenings. The second clause after but has its own subject, my partner, and verb, prefers.

Do not leave an expressed subject without a verb. I am tired but I happy is ungrammatical because the second I is missing am. You can say I am tired but happy or I am tired but I am happy.

But not is useful when the first thing or action applies and the second does not: tea but not coffee. Not negates only the second contrasted part.

After but not, use a unit at the same level: noun phrase + but not + noun phrase, or verb phrase + but not + verb phrase. In the simple I drink tea but not coffee pattern, do not add likes or drinks after not.

For a full negative statement, give it its own subject and auxiliary: I drink tea, but my sister does not. This lesson focuses on simple coordination, not every type of verb substitution.

And simply adds information, or offers a choice or alternative, and but marks contrast. The conjunction changes how the listener connects the second part with the first.

I am tired and happy is grammatical: it adds two states. I am tired but happy is also grammatical, but the speaker emphasises that happiness is unexpected alongside tiredness. And is therefore not grammatically wrong; it simply does not meet an explicitly stated goal of showing contrast.

Similarly, or is entirely correct in Tea or coffee?, but it expresses a choice. In a closed-answer exercise, but can be the only accepted answer only when the instruction explicitly requires contrast.

A comma is often omitted before but between two short parts sharing one subject: She is tired but wants to finish. Between complete clauses, especially with different subjects, a comma can help readability: She is tired, but Leo wants to continue.

In real texts, comma choice depends on length, subjects, and style; omitting a comma before but is not always a grammatical error. Open-ended answers in this material are therefore not rejected solely for a comma variant if the connection is clear.

A sentence can begin with But in ordinary speech and informal writing: But I don’t have time. Very formal writing often avoids such an opening. This stylistic distinction is not the target skill at A1.

First identify two real or invented facts. Then decide whether the second merely adds information or actually differs from the first or overturns an expectation. Choose but only for the second kind of relationship.

For a short answer, start with reliable patterns: adjective but adjective; verb phrase but verb phrase; clause but clause; A but not B. Then check that each expressed subject has the verb it needs.

Models in open-ended exercises show one natural way to answer. Vocabulary, details, and the order of the two facts can vary if the required meaning, grammatical form, and contrast are preserved. Your facts can be invented.