The emergency exit doors are used to facilitate evacuation （疏散）that are not normally used for exit 紧急出口门用于方便疏散，通常不用于出口
A.The emergency exit doors are known as, backup exit and they should not be used in special condition B.The emergency exit doors are used for the escape and are not used as the normal exits. C.The emergency exit doors are applied to board that are not usually used for exit.正确答案B
