Yah, I have been here only three months!

是啊, 我在这儿三个月!

I have been here since nine this morning.

我从今天早晨九点钟一直在这里。

I have been here since last week(month, year etc. ).

我从上周（上月、去年等）起一直在这里。

Well, I have been here since yesterday, and three flights have been canceled.

我昨天就在这里了，三架航班取消，我们什么都做不了。

“I have been here a long time and have become well accepted in this state,” he said. “They treat me like a local with a funny accent.

“我在这里已经很久了并为这个国家所接受了”，他说，“他们对我就像对一个有着奇怪口音的本地人一样。”