题目

   Traveling is one of the most important activities and people have been interested in it for many years. Modern traffics develops fast, so traveling to different places has become much easier than before(比以前更容易).    Staying healthy： while traveling can make your trip happier. But do you know how to keep healthy during a trip? The following information may be useful for you.    Before leaving: ●     Wear comfortable shoes, a hat and sunglasses. ●     Take some necessary medicine with you. They can be used when you get sick or have other problems. ● �2．当外界溶液浓度低于红细胞细胞质的浓度时，一定出现的情况是（　　）A．细胞皱缩B．细胞涨破C．发生质壁分离D．体积膨胀