Translate the following sentences.

1.我叔叔已去过美国两次,但我从没去过。

My uncle has been to America twice, but I have never been there.

2.Nick 在哪里？他去了图书馆。

Where is Nick? He has gone to the library.

3.Kitty和爸爸妈妈去了香港，她们一个礼拜之后回来。

Kitty and her parents have gone to Hong Kong. They will be back in a week.