阅读理解

    Being outgoing is good for your life. Those who are more outgoing may have more fun in life. In fact, being outgoing is not so hard as you think. Even shy people can be outgoing.

    You can start becoming outgoing with your best friends or a group of friends. But the real challenge（挑战）comes when you meet strange people. Smile more, and usually they will return your smile. In this way, you may have some more talks.

    Start a talk. Just a simple "Hello" or "How is it going” is a good start. If you want to make interesting talks, you should read news in the newspapers and prepare（准备）your views, or surf the Internet for new information and then keep that in mind.

    The easier way to become more outgoing is to go out. This is also the most important step. Go to a park, the beach, a club, a party or any other places that you think can be fun, and you may make new friends there.

下列潮湿的气体不能用固体的氢氧化钠干燥的是（　　）