The indefinite article a(n), derives from the old English word an meaning "one". Generally this word only occurs in determiner function before noun phrases which are singular. However, there seem to be some cases where this determiner occurs before plural noun phrases. I say that, but actually these noun phrase seem so bizarre to me, in terms of their structure, that I'm not sure they're definitely noun phrases at all. Here are some examples:
- a full three months before we left
- an amazing two days
- an awkward ten minutes
Ignoring the article here for a moment, these noun phrases are odd because the adjective is occurring before the numeral. We would normally expect to see:
- three full months
- two amazing days
- ten awkward minutes
Even given the oddness of the word order in the original phrases, I can see no reason why the normally singular indefinite article is licensed here.
Can anybody give an account of the syntactic structure of these phrases, and/or explain why the semantically singular article is able to be used with such phrases - even if they compulsorily trigger plural verb agreement?
Here is an example of one of these instances which seems to demand a plural verb:
- An amazing two million people attend every year.
- *An amazing two million people attends every year. (ungrammatical)