story: I told Frankie to go to the store and get groceries. He put on his jacket and went on his way. After fifteen minutes I heard a knock on the door. I wasn't expecting Frankie for another hour but there he was. When I asked him how he came and went so fast he said he ran!
 selected sentence: After fifteen minutes I heard a knock on the door.
I hear a knock on the door >Causes> I feel(s) surprised