It was preposterous of them to think that I would pay their bill without questioning the added charges.
A two-headed dog is preposterous.
'Would you like this candy or these desserts to follow the meal?'This is being used as an indicator for a singular item, and these is being used as an indicator for multiple items.See the related...
I have decided to clean out my garage next week. - as a verb we are having a clean out at home on the weekend. - as a noun