Every supporting sentence in a paragraph must relate to the main idea stated in the topic sentence. A sentence that does not support the main idea does not belong in the paragraph, thus such a sentence should be omitted. When a sentence does not belong in a paragraph, it is called an irrelevant sentence.
Example: The students in the class come from many different part of the world. Some are from European countries, such as France, Spain, and Italy. Others are from Middle Eastern countries like Saudi Arabia and Israel. Still other students were born in Asian countries, including Japan and Korea. Korean food is delicious. The largest number of students is from Latin American countries like Mexico, Venezuela and Peru. The class is an interesting mix of people from many different countries.
