`1` B 

- the role of sth : vai trò của cái gì đó

- Dẫn chứng : "If you want to take full advantage of the Internet, there is only one real way to do it: learn English" ... In fact, knowledge of English is one of the most important aspects that help you use the Internet. 

`2` D

- Dẫn chứng : Learning to use a new Internet service may take a few hours , a few days , or some weeks , but it take years to learn a language so that you can use it fluently and confidently. 

`3` B 

- Dẫn chứng : Learning to use a new Internet service may take a few hours , a few days , or some weeks , but it take years to learn a language so that you can use it fluently and confidently. 

`4` A (widely = commonly : phổ biến)