题目

听下面一段独白，回答问题。 （1） What is the main purpose of the loud noises? A . To warn people outdoors to get inside. B . To get people's attention inside their homes. C . To inform people without radios about danger. （2） Who decides to turn on the system? A . Local media. B . Local officials. C . The national weather service. （3） Where does the speaker advise people to go after hearing a warning? A . To a window. B . To a public shelter. C . To the middle of a building. （4） What is the main topic of the talk? A . A wea在x+)=x2+