5.124 prepositional phrases

However, prepositional phrases are more commonly used. The following prepositions are used in adjuncts of duration:

• after, before, for, from, in, since, throughout, to, until

The prepositional object can be a noun group referring to a specific period of time. This can be in the singular after the determiner 'a' (or 'one' for emphasis), or in the plural after a number or quantifier.

The noun group can also refer to an indefinite period, for example expressions such as 'a long time', 'a short while', 'a while', or 'ages', or plural time words such as 'hours'.