They have gone to England,and they will go back next week.
（已经去了某地方,还没回来.）
They have been to Paris.
（曾经去过某地方,强调去过）
They have been in England for two weeks.
（在某地方有呆过,强调“呆”的延长性）
They will go to England next week.
（强调要去哪个地方,瞬时性的）