关于英语完成时的题目.1.改错：We have opened the door for 3 hours.可不可以改成:

关于英语完成时的题目.
1.改错：We have opened the door for 3 hours.
可不可以改成:
[The door has been opened by us for 3 hours.]?
2.Many people have started to join our group since it began.
(改为一般过去时态)
麻烦解释一下,我英语不是很好.
The door has been opened by us for 3 hours
The door has been open for three hours
这两个句子有什么区别吗?