1. A frame before an opinion
I think helps you present an evaluation or uncertain information in your own voice. I think the bridge is beautiful — an evaluation; I think the shop closes at nine — an assumption about a fact that can be checked.
A useful opening pattern is: put I think, I believe, or In my opinion at the beginning, followed by a complete sentence with its own subject and verb. These phrases can also appear in other positions, but here we are practising this one.
I think / I believe / In my opinion + complete sentence
I think the new bridge is beautiful.
I think the new bridge is beautiful.
Beautiful is an evaluation, so the frame I think is useful.
In my opinion, the weather is too hot today.
In my opinion, it is too hot today.
The phrase In my opinion opens the sentence and is separated by a comma.
I believe that this neighbourhood is safe.
I believe that this neighbourhood is safe.
A separate sentence, this neighbourhood is safe, follows the frame.
2. I think and I believe
The frames I think and I believe have the structure subject + verb. You can put that after them, or leave it out: the meaning is the same. In conversation, people more often speak without that.
I think is common in everyday conversation. I believe may sound more formal or emphasise conviction; the strength of the confidence also depends on context and intonation.
I think (that) + sentence; I believe (that) + sentence
I think that our teacher is very kind.
I think that our teacher is very kind.
You can leave out that: I think our teacher is very kind.
I believe our plan is realistic.
I believe that our plan is realistic.
I believe shows conviction. Is comes after the subject our plan.
3. In my opinion
The phrase In my opinion always uses the preposition in. The alternatives on my opinion, at my opinion, and by my opinion are common mistakes.
At the beginning, In my opinion is usually separated by a comma. It is a familiar phrase for expressing your own evaluation. According to usually refers to a source of information, so choose In my opinion for a simple personal opinion.
In my opinion, + sentence
In my opinion, the first lesson was the best.
In my opinion, the first lesson was the best.
After the comma comes a regular sentence with the subject the first lesson.
In my opinion, this dress is too bright.
In my opinion, this dress is too bright.
Too bright is an evaluation, and the frame introduces it.
4. After the frame — a complete sentence
The frame only introduces the opinion. The sentence that follows it is built like a regular affirmative sentence: subject, then verb (often is or are), then the rest. The word order does not change as it does in a question.
In the pattern think + complete sentence, be is needed before an adjective: I think this idea is good. There is also the formal construction think + object + adjective, but here we are practising the simpler pattern with a complete sentence.
frame + subject + verb + the rest
- subject / S —
- The grammatical subject: who or what the clause is about; the verb agrees with it. In The book was written, the book is the subject, although someone else does the action.
- verb / V —
- A word for an action or state, such as work or be. The pattern determines its form.
I think the neighbours are friendly.
I think the neighbours are friendly.
The subject the neighbours is plural, so use are.
I believe that the trains are late today.
I believe that the trains are late today.
After that comes a separate sentence with the subject the trains.
5. Negation: I don't think
To say “I don't think that…”, put the negation in the frame: I don't think. The sentence after it remains affirmative: I don't think the restaurant is cheap. You can also say I think the restaurant isn't cheap, but in this rule we are learning the form I don't think: the negation is in the frame.
This sounds softer than a direct negative statement. A double negative (I don't think … isn't) changes the meaning, so avoid it.
I don't think + affirmative sentence
I don't think the restaurant is cheap.
I don't think the restaurant is cheap.
Don't comes next to think, while is cheap remains affirmative.
I don't think these shoes are comfortable.
I don't think these shoes are comfortable.
The subject these shoes is plural, so use are.
6. Think about and think + sentence
Think about + a noun means “consider or reflect on something”: I think about my holiday. There is no evaluation here; there is only the subject of the thought.
Compare “I think about my holiday” and “I think my holiday was wonderful.” For the second meaning, say I think (that) my holiday was wonderful, without about before this sentence.
think about + noun ≠ think + sentence
- noun —
- A word naming a person, thing or idea: student, book, happiness.
I think about my holiday.
I think about my holiday.
The noun my holiday follows about; there is no evaluative opinion.
I think my holiday was wonderful.
I think my holiday was wonderful.
A complete sentence with the evaluation wonderful follows think.
7. Opinion, reason, and softening
The frame shows your position. To explain it, you can add a reason with because or use a separate sentence.
The frame is not necessary every time: you can state a fact without it (The shop closes at nine). But for evaluations such as good, boring, and expensive, the frame makes the language more polite.
frame + opinion + because + reason
I think this dress is nice because the colour is bright.
I think this dress is nice because the colour is bright.
Because answers the question “why?” and introduces a new sentence.
In my opinion, the dessert is sweet. I like it.
In my opinion, the dessert is sweet. I like it.
You can give the reason or explanation in a separate short sentence.
8. Limits of the rule
Here we are learning how to express your own opinion. Questions such as What do you think? and answers such as “I agree / I disagree” belong to related rules in this topic.
I think can be used both with evaluations and with assumptions about facts that can be checked. The frame does not change whether the statement is true; it shows how the speaker presents it.
here: express your opinion; not here: ask for an opinion or agree
I think the shop is too small.
I think the shop is too small.
This is a personal opinion, not a question or an expression of agreement.
What do you think of the shop?
What do you think of the shop?
This is a question about someone’s opinion; it is taught separately.
Common mistakes
Incorrect:On my opinion, this soup is salty.
Correct:In my opinion, this soup is salty.
The English phrase uses the preposition in; on, at, and by do not work here.
Incorrect:I think this soup are salty.
Correct:I think this soup is salty.
Soup is singular here, so the complete sentence needs is.
Incorrect:I think about the weather is cold.
Correct:I think the weather is cold.
Before the complete statement the weather is cold, this pattern needs think (that), without about.
Incorrect:In my opinion, the test be easy.
Correct:In my opinion, the test is easy.
In an ordinary statement in the Present Simple, the test needs the form is.
Incorrect:I am think this movie is good.
Correct:I think this movie is good.
In the Present Simple, do not add am before think. For an ordinary evaluation, I think is enough.