阅读理解

A

　Here are some English study skills for beginners.

　　★Listening

　　Listening is a great way to improve your pronunciation and intonation (语调). You can start by listening to short stories for children because they are usually easy.

      ★Reading

　　Reading is a good way to help you learn new words. And it will also help you learn English grammar. Children's books are great for beginners.

       ★Vocabulary

　　When you come across new words in the reading, write them down in your notebook. You can write down the translation in your native language to help you understand.

  　★Speaking

　　While doing your reading exercises, read them aloud.You can also look for some articles on the Internet to read.

 　　Learning any language needs practice—lots of practice.You don't have to spend hours studying each day; just 30 minutes a day for four or five days a week will help you improve it.

列宁说：“一个民主国家必须承认各地区的自治权，特别是居民的民族成分复杂的地区和专区的自治权，这种自治区同民主集中制一点也不矛盾；相反的，一个民族成分复杂的大国只有通过地区的自治才能够实现真正的民主集中制。”据此，我们可以认识到新中国的民族区域自治制度（   ）
①促进了社会主义民主政治的发展    ②保证了祖国统一和民族团结
③实现了少数民族的高度自治        ④促进了民族地区的社会进步

图中是抛物线拱桥，P处有一照明灯，水面OA宽4m，从O、A两处观测P处，仰角分别为α、β，且tanα= $\frac{1}{2}$ ， $\tan \beta =\frac{3}{2}$ ，以O为原点，OA所在直线为x轴建立直角坐标系．

（1）（$\sqrt{3}$+$\sqrt{6}$）²

（2）4$\sqrt{5}$+$\sqrt{45}$-$\sqrt{8}$+4$\sqrt{2}$

（3）$\sqrt{18}+{\left(\sqrt{2}+1\right)}^{-1}+{\left(-2\right)}^{-2}$

（4）$\frac{2}{3}\sqrt{3\frac{3}{5}}\times \left(-9\sqrt{45}\right)$．

如图，矩形ABCD∽矩形ECDF，且AB=BE，求BC与AB的比值．