And how will I master English grammar, it is very difficult for me
What you can do
Be aware of grammar. Think about grammar. Notice the aspects of English grammar that are the same as or very similar to those in your language. (The use of the articles in German, for example, is similar to their use in English.) Notice also the way that English expresses an idea differently to how it is done in your language. For example, English uses the present perfect to express a period of time that started in the past and continues in the present (e.g. I have had this watch for 10 years). Many other languages use the present tense to express the same idea; (e.g. German: Ich habe diese Uhr seit 10 Jahren.) If you notice grammar similarities and differences, you will probably learn the rules more quickly.
Read a lot of English books - this may sound strange but in fact all the time you are reading English (and also listening to English), you are taking in models of correct grammar that will help you in your own writing and speaking. It will help you when you express your ideas and when you come to check your work. Of course, it is even better if you can read with the grammatical awareness discussed in the last paragraph. By this I mean that you say to yourself from time to time: Ah, so that's how you do this in English!
I think it's helpful to know how your language and English are different ie. subject + verb + object and what kind of things exist in English. But I would recommend against doing the grammar-translation method because it will cause Chinglish.
The problem I had was I spent too much time with grammar in the beginning and it made me very self-conscious of making mistakes. Rather, try to find something you enjoy in English, whether it's a movie, etc and ask native speakers to help you what certain sentences mean. You can save those sentences on a flashcard and practice them. Don't try to analyze excessively about grammar rules in the early stages is my opinion, it will come naturally the more you are exposed to native speech.
谢谢victor，你的建议
I great with Gigi said. Be aware the differences and similarities between English and your language.The first thing that you have to notice the rule of sentences, how to put the wards together in a sentence.Also you should notice how the native speakers express their ideas.Maybe the sentences you say or write is right,but not natural way to express English.
