last year是什么词性

词性是名词短语，例如：

1、Who could forget his speech at last year's party?谁能忘记他去年在聚会上的讲话呢

2、The house came on the market last year.这栋房屋去年就上市了。

3、This year's results are virtually the same as last year's.今年的结果几乎和去年的一样。