Here’s a possible way to fill in the blanks:

(28) **As**
(29) **with**
(30) **the knowledge**
(31) **fluently**
(32) **through**

So the completed text would read:

The internet becomes more and more popular in our life. (28) **As** Internet services are rather easy to use, you will have considerable difficulties if you are not familiar (29) **with** English. In fact, (30) **the knowledge** of English is one of the most important aspects that help you use the Internet. Learning to use a new Internet service may take a few hours, a few days, or some weeks, but it takes years to learn a language so that you can use it (31) **fluently** and confidently. Of course, when you know some English, you can learn more just by (32) **through** it on the Internet. But at least your English should be good enough to understand commonly used words and to know what to do on the Internet.