Question 1: Members may keep books for 3 weeks.
Books can be kept for 3 weeks by members.

Question 2: No one in my group is more intelligent than Mary.
Mary is the most intelligent person in my group.

Question 3: They are looking for the man. He has lost the way in the forest. (who)
They are looking for the man who has lost his way in the forest.

Question 4: Thu said: "All the students will have a meeting next week".
Thu said that all the students will have a meeting next week.

Question 5: "Where are you going?" he asked her.
He asked her where she was going.