题目

 I always sleep with the windows open       it’s really cold or rains heavily. A. when                               B. if                                    C. unless 答案：C当火灾发生时，下列措施可行的是（　　）A．跳楼逃跑B．有烟雾的地方要蹲下或匍匐前进C．室内失火时，立即打开所有门窗，尽量让浓烟从门窗排出D．向楼道跑