Tag questions (short answer) in declarative sentences:
A tag is formed by taking the helping verb of the main verb (make it a question to find the helping verb).
Everybody forgot to congratulate her.
Did everybody forget to congratulate her?
TAG: Everybody forgot to congratulate her, didn't they?
Main verb: forget Tense: simple past (forgot).
Also, don't forget that in a declarative sentence tag, the tag must be negative interrogative (didn't they?). In a negative sentence, the tag must be plain interrogative (They didn't forget to congratulate her, did they?).
You can practice with these:
The boys have found the dog and brought him home. [tricky, kind of]
You will be going to school this afternoon.
We wouldn't have been in town so late, normally.
Clues: the helping verbs are either in the sentence (have, will, is/are, would/should) but in the present and simple past, you have to come up with [do/does and did).
You speak Russian, don't you? You have to remember that do is the helping verb.
This is just a basic introduction, not the whole entire story.
Here is an important irregularity:
I'm being clear, aren't I? :) [regular]
VERSUS I'm being clear, am I? [in response to praise or to be sarcastic, for example]
That one does not follow the rules, you just have to learn it. First person sentence in the present tense with a tag.
Also, in a negative sentence: I'm not being clear, am I?
Best Answer
This isn't a statement about the character of the British. This is a statement about perception, about what other people think. The verb of the independent clause is "think". This statement happens to contain a subordinate clause with the verb "are".
In a tag question, the tag is another clause which attaches to an independent clause:
In your example, the verb of the main clause accepts do-support. The verb of the subordinate clause does not. In another statement, both verbs could accept do-support:
If the tag could apply to either the independent or the subordinate clause, this would be an ambiguous question: don't people think that? or don't the British hate coffee? Instead, the tag can only apply to the independent clause, and the only available interpretation is don't people think that?
We could ask a follow-up question about whether the British hate coffee, but that follow-up question would not be a tag:
The follow-up question here is an independent clause and a separate sentence. Since the tag would be "don't they", the natural follow-up is "Do they?". "Don't they?" is a grammatically possible follow-up, but it's too easy to mistake for a tag in this context.
We could even ask a follow-up question if the verb of the subordinate clause does not accept do-support:
Here, both "Are they?" and "Aren't they?" are reasonable follow-up questions, since neither one can be mistaken for the "do they" tag that could attach to the independent clause of the original statement.
The model in the test question is punctuated as a single sentence. You need to pick the answer that works as a tag, not as a separate follow-up question.