been, gone, come

been to意为“已到过某地且已经返回”；gone to意为“已去(或已到)某地但尚未回来”；come意为“来了而且仍然在这里”。

试比较：

I have been to New York twice.我去过纽约两次。

The postman's already been. (He has come and gone away again.)

邮递员已经来过了。

Jane's come, so we can start work. (She has come and is still here.)简来了，所以咱们可以开始干活儿了。

She has gone out to shop. 她到商店去了。(还未回来)