I built a house last year.为什么冠词用a而不用the

问题描述:

I built a house last year.为什么冠词用a而不用the

I built a house last year.着重说明“去年我建了一所房子”这个事实.
I built the house last year.是说“去年我建了这所房子”,特指这所房子是去年建设的.