Question

现在完成时have后什么时候后面加been？

Answer 1

回答如下：
现在完成时的结构是助动词have /has + 过去分词。英语be动词 ( am，is，are)的过去分词是been，所以句子中有be动词时，其现在完成时应该是助动词have / has + been + 其他。例如：
1. I am ill.
I have been ill.
2. He is in the room.
He has been in the room.
3. They are injured.
They have been injured.
4. It is five years since he died.
It has been five years since he died.

Answer 2

have done现在完成时的主动语态。是主动的，主动做的，过去动作影响现在。或过去状态持续到现在。如：They have done the experiments.
have been done现在完成时的被动语态。是被动的，也就是被做的。如：The experiments have been done.Her hair could have done with a wash.

　　她的头发该洗一洗了。

　　I could have done without being woken up at three in the morning.

　　其实用不着在凌晨三点钟就把我叫醒。

　　They have been working on the perfection of the new model.

　　他们一直在努力完善新型号。

Answer 3

动词是be的过去分词
如
I have been to Beijing.

我曾经去过北京。