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

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
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?

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
1 可以啊,你这样是正确的
2 只是改为一般过去时,主句和从句都要变一下,many people started to join our group when it begins