概括段落大意和补全句子
阅读下面短文,请完成短文后的2项测试任务: ( 1 )题后所给的6个选项中为第①~⑤段每段选择1个正确的小标题; (2)从题后所给的6个选项中选择5个正确选项，分别完成每个句子,并选择正确的答案代码(指 A、B、C、D、E或 F)。

     ①The English language is used by more people in the world than any other language today. This may seem surprising at first. After all, the population of English native speakers (mainly from United Kingdom, United States, Canada, Australia and New Zealand) is one of the smallest in the world. The total only comes to about 400 million, which is less than one-tenth of the population of the world. If we count all the English-speakers in India, Singapore and some other countries, that adds another 700 million to the total. Add all those people who speak English elsewhere and the total English-speaking population of the world comes to an impressive one and a half billion. 

     ②Why is this? There is one important historical reason: the influence of the British Empire-the Empire that stretched across the globe. Although the Empire no longer exists, the English language is firmly rooted in its former colonies （殖民地）- in African, India, Pakistan, Bangladesh, the Far East, Australia, New Zealand, the Caribbean and North America. 

     ③Other important reasons for the spread of English language are economic. English is the language of international business and commerce. Also, most scientific and technological developments have been made by English-speaking societies. To keep up with such developments, to talk about them in international conferences, or write and read about them in scientific journals and books, scientists, scholars and students must be able to understand English. 

     ④There is also a rather less obvious reason. English is the language of a popular culture. All over the globe, millions of young people listen to pop music and watch pop videos. The stars who perform in English are by far the most famous. Hundreds of American and British singers can be heard all over the world. English has become an international language. 

     ⑤English is well suited to this role. Unlike many other languages, it has a built-in flexibility（灵活性）that allows constant adaptation（改编）and assimilation（同化）. In English, vocabulary from other languages is often used, new words and combinations of words can be coined（杜撰） easily, nouns can be turned into verbs and vice versa. Thus, what is correct in English is often, simply, what is accepted as appropriate and understandable by those who speak it, whether they are native or non-native speakers.