I came across these two examples, given to illustrate 'a case' where the inclusion of the preposition for is considered optional in the paper "Acquisition of Preposition Deletion by Non-native Speakers of English" by the authors Jae-Min Kim and Gil-Soon Ahn (in §2, on p.3):
a. We have lived here (for) 12 years.
b. I've studied English (for) ten years.
Though I have no problems with either version of the (a) sentence, omitting the preposition in (b) sounds unacceptable to me.
Is this regional?
Is acceptability influenced by
- the size of the DO (/locative / PP / …) between the verb and the time phrase
- the actual verb used
?
Please note: The referenced paper is very useful, but contains a few expressions that need minor corrections – possibly translation errors.
Best Answer
Some personal observations that won't fit in a comment box. Firstly, as a rule of thumb it seems better to use such noun phrase Adjuncts of duration (i.e. those which occur with numbers, e.g. five minutes, three days, a year) with stative verbs, verbs that describe situations and not real actions:
These usages are more common, I believe, in American English than in British English. However, in British English they seem massively improved if there is another preposition phrase after the duration phrase. One example is the word now:
Notice that we shouldn't confuse these duration Adjuncts NPs with temporal NPs functioning as the Complement of a verb. Several verbs take such NPs as a Complement: