1.They came here in autumn.
= They (have been) here (since autumn).
2.The Greens went to Sanya in February.
= The Greens (have been in) Sanya (since February).
这两题都是考查一般过去时和现在完成时的转换.
如果你满意我的答案,这是对我们答题者劳动的尊重,多谢!