常年使用的钢筋堆放场地（工厂化生产）最好选择有很好排水设施的水泥地面上，铺设距离地面（）cm高的方木或石条上。

A、不低于5

B、不高于15—20

C、不低于20—30

D、不高于10—15

理想的幼儿园户外活动场地是（)。
A．大面积水泥地，四周有高大的树木
B．大面积水泥地，中间有水泥花坛、长廊，四周有树
C．大面积草坪，四周植树，中问有可供幼儿攀登的假山
D．大面积草坪，各班的活动场地以矮小的树木花卉隔开；全园有一块一定面积的水泥地，四周有高大的树木，边缘设有凉棚

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？
A．windows.
B．elevators.
C．fire escapes.
D．stairways.