Remember that 'a/an' and 'one' can mean a numerical 1. When we say 'one' it is often for emphasis and to be specific about the number so that it is clear. 'One' is also used a pronoun therefore it can stand alone.
Examples with 'one':
- "They only had one pair of shoes left in my size."
- "I have one sandwich to spare, would you like it?"
- "I'm having a beer, would you like one?"
Examples with 'a':
- "I can give you a ticket, I've got two going spare."
- "I'll buy you an ice cream if you'd like one?"
- "Do you fancy a break now or later?"
Watch the video and try Nick's mini test.
What's missing 'a', 'an' or 'one'?
- Where can I get ________?
- Do you know if there is ______ spare ticket left?
- I'm ordering ______ G&T, do you want _____?