The USCIS (United States Citizenship and Immigration Services) test is designed for people who are not native speakers of English. But the test questions assume that the people being tested for citizenship have a basic knowledge of English. As you prepare for the USCIS test, you should have two goals:
The USCIS citizenship test is not a test of specific grammatical concepts in English. It is a test to determine whether or not you have the basic skills to communicate. Therefore, you should do all you can to gain the experience and practice that will help you to develop your communication skills.
To be a good citizen of the United States, you need to know English. It is the language used by most people in the United States. Although there is no "official language" of the country, a basic knowledge of English is required to become a citizen. That is the reason for the oral interview and for parts of the written test: to determine whether or not you can speak and understand English and whether or not you can read and write adequately in English.
A good citizen reads newspapers and magazines to know what is going on in the country. A good citizen listens to radio broadcasts and watches television to get the latest news. A good citizen has to be informed. And knowing basic English is the key to the information that will make you a good citizen and a well-informed voter.
If you were not born a native English speaker, you may believe that your English is poor. Do not let that worry you. To become an American citizen, you do not have to speak and write perfect English. Many Americans speak using incorrect grammar. Many have foreign accents. That's actually a part of America, for this country is a nation of immigrants. Your goal for yourself should be to improve your level of English and to go to the USCIS citizenship test prepared to speak and write as best you can.