同义转换: has gone
has been 去过（人已经回来了）has gone 去了（人还没回来，人在那边）
He has been to Beijing.
他去过北京.（现在不在北京）He has gone to Beijing.
他去了北京.（现在人在北京）
The water has gone cold.
水已变凉。
The offer has been withdrawn.
那个报价已经撤销了。
He has been in Beijing for 10 years. =He has been in Beijing since10 years ago.
