一个直角梯形下底是18分米，如果把上底增加6分米，就变成了长方形，面积也增加了48平方分米，这个直角梯形的面积是____平方分米

如图所示的家庭电路中，闭合开关后灯泡不亮。用试电笔检测插座的两孔，发现只有插入右孔时氖管才发光。用试电笔检测A点氖管发光，检测B点氖管不发光。发生这一现象的原因可能是（   ）

以下各式中错误的是（　　）

阅读短文，根据其内容回答问题。
These days, many Chinese people are happy about a piece of news. What is it? China may become the second largest economy (经济体) in the world. It’s only behind the US.
But is China the second richest country, too?
No. The economy is like a cake. The US, Japan and China each makes one. China makes the second biggest cake. But lots of people have to eat it. Why? There are 1.3 billion people in China. And there are only 300 million people in the US and 127 million in Japan. So, in China, each person only gets a very, very small piece of cake. But people in the US and Japan have bigger pieces.
China is not as rich as the US and Japan. For example, in the US, in every 100 people, 75 can surf the Internet; in Japan it is 74 in 100. But in China, only 26 people in 100 use the Internet.
China’s large economy brings good things. People in China have more jobs and money. We also have more influence (影响) in the world.

晋朝人张翥，少年时就显示出才华，但是，他不在读书上下功夫，也不知道约束自己，踢球不知收场，摆弄乐器没有节制。他父亲很担忧，怕他长大了不务正业，而他自己却没认识到这样玩闹下去前途不堪设想。这说明人最难战胜的敌人就是自己，人的弱点包括 （）
①自己的惰性；   ②自己的缺点和错误；
③自己的不良习惯；④自己能够控制和约束自己