since last year是什么时态
since +过去的时间,用于现在完成时，所以since last year是现在完成时；
现在完成时( The Present Perfect Tense)是过去的动作或状态持续到现在，对现在造成的影响，可能持续发生下去。在英语时态中，“时”指动作发生的时间，“态”指动作的样子和状态。
The hotel has polished up its act since last year.
这家酒店自去年以来已经改善了服务水平。
Our problems have multiplied since last year.
自去年以来，我们的问题成倍增加。
Violent crime has increased by 10 percent since last year
暴力犯罪自去年以来增加了10%。
The manufacturing industry has contracted by 1.5% since last year.
自去年起，制造业已经萎缩了1.5%。
He hasn\'t been home since last year.
自从去年至今他未回过家。