Complete the sentences with by, for, in or on.
1 I visited Paris _______ the tenth time last spring. It’s my favourite city.
2 After waiting 30 minutes, the bus still hadn't come, so I decided to go home _______ foot.
3 Why did you travel to the Antarctic _______ the first place? It was never a good idea!
4 I thought there was coffee in the cup, but _______ fact, it was Chinese tea.