单选题
Firefighters are often asked to speak to school and community groups about the importance of fire safety, particularly fire prevention and detection. Because smoke detectors reduce the risk of dying in a fire by half, firefighters often provide audiences with information on how to install these protective devices in their homes.
Specifically, they tell them these things. A smoke detector should be placed on each floor of a home. While sleeping, people are in particular danger of an emergent fire, and there must be detector outside each sleeping area. A good site for a detector would be a hallway that runs between living spaces and bedrooms.
Because of the dead-air space that might be missed by hot air bouncing around above a fire, smoke detector should be installed either on the ceiling at least four inches from the nearest wall, or high on a wall at least four, but no further than twelve, inches from the ceiling.
Detectors should not be mounted near windows, entrances, or other places where drafts (过堂风) might direct the smoke away from the unit. Nor should they be placed in kitchens and garages, where cooking and gas fumes are likely to cause false alarms.
单选题
One responsibility of a firefighter is to ______.
【正确答案】
C
【答案解析】[解析] 本题的依据句是文章的第一个句子“Firefighters are often asked to speak to school and community groups about the importance of fire safety, particularly fire prevention and detection.”。其他的选项在文章中找不到依据。
单选题
Compared with homes without smoke detectors, homes with them give their owners a 50% better chance of ______.
【正确答案】
B
【答案解析】[解析] 本题的依据句是文章的第二个句子中前半句话“Because smoke detectors reduce the risk of dying in a fire by half.”。B项的“surviving a fire”意思为“幸免于一场火灾”，与原句的意思完全一致。
单选题
A smoke detector must always be placed ______.
【正确答案】
B
【答案解析】[解析] 本题的依据句是第二段第二个句子“A smoke detector should be placed on each floor of a home.”。B项中的“any levels”相当于依据句中的“each floor”。其他选项属于错误信息或无关信息。
单选题
The passage implies that dead-air space is most likely to be found ______.