I’ve been waiting for an hour and he still hasn’t turned up. 我等了一个小时,可他还没来.上面这句话中,为什么用hasn't（he still hasn't……）?haven't\hasn't 一般在什么时候用?......重点是为什么用hasn’t？三

I’ve been waiting for an hour and he still hasn’t turned up. 我等了一个小时,可他还没来.
上面这句话中,为什么用hasn't（he still hasn't……）?haven't\hasn't 一般在什么时候用?
......重点是为什么用hasn’t？三单也可以用doesn't啊，不是么？

haven't 意思是"还没有",后面要跟动词
I haven't eaten yet.我还没吃饭的
I haven't finished.我还没干完呢