Great subject! First, what are interjections? Interjections are words and phrases used to express a strong feeling or emotion. Interjections stand alone and are not usually part of a true sentence. Remember that all sentences must have a verb. While it is common to place an interjection at the beginning of a statement, they can go just about anywhere! Interjections are followed by an exclamation mark or comma. An interjection can express “Surprise, joy, excitement, enthusiasm or disgust.” Any word in the English language can be used as an interjection. “Yes” is one of the most commonly used words in the English language. It is an “Adverb.” At least that is what we are taught in school. “Yes” also falls into another entirely different part of the English language. If used completely alone without other words or a follow-up sentence, “Yes” can also be referred to as a “Minor Sentence!” This is only if there is no further statement added and the listener knows what you are referring to. “Yes” can be used to express positive and negative thoughts and is also used as a verb and noun! Ask your teacher to explain this subject further with examples!