---Do you know the man is reading the book over there? ---Yes, he’s Mr. Green, our PE teacher.
-Please keep the secret _______me. -OK. I’ll keep it _______myself.
Why was the house on fire? _______ lightning hit it.
Please _________for my car.
He found _________important to protect wild birds.
The teacher asked us to keep quiet. Which kind of structures does the sentence belong to?