What is a conjunction?
A conjunction is a joining word. It joins words, groups of words or whole sentences.
Example: tea and biscuits. I was tired but I went.
Coordinating conjunctions: and, but, or
These join equal parts. Each part can stand alone as a sentence.
| Word | Job | Example |
|---|---|---|
| and | adds | I like tea and she likes milk. |
| but / yet | opposite idea | It was late but we waited. |
| or | choice | Walk or take a bus. |
| so | result | It rained, so we stayed in. |
Put a comma before the joiner when it joins two full sentences.
Subordinating conjunctions: because, when, if
These start a small clause that depends on a main clause. The small clause cannot stand alone.
| Word | Shows | Example |
|---|---|---|
| because | reason | I stayed home because it rained. |
| when / while / after | time | I smile when I see you. |
| if / unless | condition | If it rains, I stay home. |
| although | surprise | Although I was tired, I went. |
If the small clause comes first, put a comma after it.
Modal verbs: can, may, should, must
A modal verb is a helper verb that adds a feeling to the main verb.
| Modal | Meaning | Example |
|---|---|---|
| can | ability, possibility | She can swim. |
| may | permission, maybe | May I come in? It may rain. |
| should | advice | You should sleep early. |
| must | strong need, rule | You must wear a helmet. |
Rules for modals
- The next verb is always the plain form: He can sing (not sings, not to sing).
- No -s for he/she/it: She must go.
- Question: modal first. Can you swim? Negative: add not. You mustn't run here. (mustn't = it is forbidden.)
- For the past of can use could; for must (need) in the past use had to.
Key formulas and definitions
- clause + and / but / or / so + clause
- main clause + because / when / if + small clause
- modal + plain verb (can swim, must go)
- question: modal + subject + verb? Can you swim?
- negative: modal + not + verb (mustn't, can't, shouldn't)
Worked examples
1. Join with a suitable word: She was ill. She came to class.
She was ill but she came to class. The two ideas go against each other, so use but.
2. Fill in: I took an umbrella ____ it was cloudy.
because. The second part is the reason, so we use because (a subordinating word).
3. Choose the right modal: "____ I borrow your pen?" (asking permission politely)
May (or Can). May I borrow your pen? May is the polite choice for permission.
4. Correct this: He can sings very well.
He can sing very well. After a modal we use the plain verb, with no -s.
5. Which is stronger: "You should wear a helmet" or "You must wear a helmet"?
must is stronger. should is advice; must is a rule or a strong need.
Common mistakes
- Writing "She cans sing" or "She can sings". After a modal use the plain verb.
- Using because and so together: "Because it rained, so we stayed". Use only one of them.
- Treating mustn't and don't have to as the same. mustn't = forbidden; don't have to = not necessary.
- Starting a sentence with only the small clause: "Because it rained." It cannot stand alone.