a single ticket的用法和样例：
- Do you want a single ticket or return ticket?
- I need a single ticket to Paris tonight.
- I want a single ticket.
- Do you want a single or a return ticket?
- DB already runs co-ordinated services with Lufthansa that allow travellers to transfer from a plane to a train with a single ticket, for example.
- Darwin also uses a bus service. International students receive concession rates on Darwin buses. Fares start at AUD$0.50 for a single ticket valid for three hours.