Rhetorical question “不是……吗？”
In Chinese the pattern “不是……吗？” (bú shì... ma?) usually conveys the speaker's puzzlement or annoyance, and sometimes a reminder or a confirmation.
The sentence looks negative in form, but its meaning is usually affirmative.
In English it usually comes out as:
Isn't it …?
Didn't you say …?
… aren't you?
Basic Structure
不是 + clause + 吗？
Meaning: isn't it …?
Examples
你不是喜欢玩电脑吗？你可以去看看跟电脑有关系的书
Structure
你 + 不是 + 喜欢玩电脑 + 吗？
you + don't you + like playing on the computer + ?
你不是……吗？ — don't you …?
喜欢玩电脑 — to like playing on the computer
你可以去看看 — you could go and have a look
跟电脑有关系的书 — books to do with computers
Here the speaker is reminding the listener of something already known.
你不是说今天有事吗？为什么来了？
Structure
你 + 不是 + 说今天有事 + 吗？
you + didn't you + say you were busy today + ?
你不是说……吗？ — didn't you say …?
今天有事 — to be busy today
为什么来了？ — why have you come?
Here the speaker is expressing puzzlement or annoyance.
考试不是下个月吗？你怎么今天就开始复习了？
Structure
考试 + 不是 + 下个月 + 吗？
the exam + isn't it + next month + ?
考试 — the exam
不是下个月吗？ — isn't it next month?
你怎么……？ — how come you …?
今天就开始复习了 — have started revising already today
Here too the speaker is surprised and asks out of puzzlement.
Quick Rule
不是 + clause + 吗？
Meaning: negative in form, but usually affirmative in sense.
The pattern is mostly used for:
puzzlement;
annoyance;
a reminder;
a confirmation.
Examples:
你不是喜欢玩电脑吗？
你不是说今天有事吗？
考试不是下个月吗？