Page 503 - Practical English Usage 3ed - Michael Swan, Oxford

5 meaning and intonation
question tags (2): advanced points 488
In speech, we can show the exact meaning of a question tag by the intonation. If the tag is a real question - if we really want to know something and are not sure of the answer - we use a rising intonation: the voice goes up.
The meeting's at four o'clock, i-sn-'t-it?
If the tag is not a real question - if we are sure of the answer - we use a falling
intonation: the voice goes d-own. It's a beautiful day, isn't it?
In writing, the exact meaning of a question tag is normally clear from the context.
6 requests
We often ask for help or information by using the structure negative statement + question tag.
You couldn't lend me a pound, could you?
You haven't seen my watch anywhere, have you?
For details of other kinds of tags, see 514.
488 question tags {2}: advanced points 1 aren't I?
The question tag for I am is aren't I? I'm late, aren't I?
2 imperatives
After imperatives, won't you? can be used to invite people politely to do things (especially in British English).
Come in, won't you?
WiLYwould/can/could you? can all be used to tell or ask people to do things.
Give me a hand, wiU you? Open a window, would you? Can't you expresses impatience.
Shut up, can't you?
After a negative imperative, we use will you?
Don'tforget, willyou?
3 let's
After let's ... (in suggestions etc, see 323), we use shall we? Let's have a party, shall we?
4 there
There can be a subject in question tags. There's something wrong, isn't there? There weren't any problems, were there?
When there's introduces a plural subject (see 532.4), the tag is aren't there? There's some more chairs upstairs, aren't there?
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