题目

Have you ever had trouble sleeping in a new place? Lots of people do. And now researchers from Brown University in Rhode Island think they know why. They found that one-half of the brain remains more awake than the otherhalf when people are trying to sleep in a new place. The sleep findings were reported in Current Biology by Brown University. In their report, the researchers said many people report they have a harder time sleeping the first night at a hotel or other places outside their home. They call it first-night influence. In Japan they say, 'If you change your bed, you can't 下列区别物质所用的方法或试剂，错误的是A．氧气和氮气﹣﹣观察颜色B．铁粉和炭粉﹣﹣用稀硫酸C．氢氧化钠和氯化钠﹣﹣加水D．白酒和白醋﹣﹣用闻气味