题目

Many deaths from home fires are the result of burns and panic, but most are caused by deadly smoke and gases. These fatal fires are often caused by such careless acts as throwing away a lighted match or cigarette, allowing rubbish to pile up, overloading electrical wires, or misuse of healing and cooking equipment.Few families go to bed at night without first checking to make sure that the doors and windows are locked, but they overlook a very basic fire safety rule. This rule states that people should sleep with their bedroom doors closed. Nighttime fires are most serious because the family i平行投影与中心投影之间的区别是 ______．