have been to do什么意思？

Question

他和have been doing,have been done,have done有什么区别？
例句：Chinese authorities say Russian experts have been on hand to support the entire mission.

Answer 1

意思就是：已做好了

Answer 2

现在完成进行时

Answer 3

已经做某事

Answer 4

曾经作过。。。。。。

Answer 5

“最近做过什么”