1. Our customers are from English-speaking countries.
Our customers aren't from English-speaking countries.
Our customers are from English-speaking countries, aren't they?
2. There was a confidential document in that safe.
There wasn't a confidential document in that safe.
Was there a confidential document in that safe?
3. She must know a foreign language in order to be a good secretary.
She must not know a foreign language in order to be a good secretary.
Who must know a foreign language in order to be a good secretary?
4. The Earth goes round the Sun.
The Earth doesn't go round the Sun.
The Earth goes round the Sun, doesn't it?
5. Alex is getting married next month.
Alex isn't getting married next month.
Is Alex getting married next month?
6. The police stopped me on my way home last night.
The police didn't stop me on my way home last night.
Who stopped me on my way home last night?
7. Yesterday Tom woke up early.
Yesterday Tom didn't wake up early.
When did Tom wake up early?
8. Lots of things have happened since I last wrote to you.
Lots of things haven't happened since I last wrote to you.
Have lots of things happened since I last wrote to you?
9. They'll have business talks tomorrow morning.
They won't have business talks tomorrow morning.
They'll have business talks tomorrow morning, won't they?