遇火灾、地震或其它灾害时，可以使用电梯。
参考答案：错
According to its content, a letter contains ______.
A. the purpose of writing the letter B. supporting informationC. sender’s address D. a routine remark
A．head=NULL
B．head-＞next=NULL
C．head-＞next=head
D．head＜＞NULL
