1.We may occupy this room. - We shall be  allowed to occupy this room. - We were allowed to occupy this room.
2.He may stay away from school. - He will be allowed to stay away from school. - He was allowed  to stay away from school.
3. The tourists may spend the night in the camp. -  The tourists allowed to spend the night in the camp. - The tourists allowed  to spend the night in the camp.
4.You may see the documents. -  You will allowed to se these documents. - You was allowed to see these documents. 
5.She may work in the laboratory - She will be allowed to work in the laboratory. - She was allowed to see these documents.
6.The pupils may go home. - The pupils will be allowed to go home. -  The pupils were allowed to go home.
7. I may be present at the meeting. - I shall be allowed to be present at the meeting. - I was allowed to be present at the meeting.