Escaping a fire is a serious matter. Knowing what to do during a fire can save a life. It is important to know the ways you can use and show them to everyone in the family, such as stairways and fire escape, but not elevators. From the lower floors of the building, escape through windows is possible. Learn the best way of leaving by the window with the least chance of serious injury. The second floor window is usually not very high from the ground. An average person, hanging by the fingertips will have a drop of about six feet to the ground. It is about the height of an average man. Of course, it is safer to jump a short way than to stay in a burning building. Windows are also useful when you are waiting for help, be sure to keep the door closed before opening the window. Otherwise, smoke and fire may be drawn into the room. Keep your head low at the window to be sure you get fresh air rather than smoke that may have leaked (渗入)into the room. On a second or a third floor, the best windows for escape are those which open on a roof. From the roof a person can drop to the ground more safely. Dropping onto cement(水泥地)might end in injury. Bushes and grass can help to break a fall. Which of the following should not be used when trying to escape a fire?