Why should you never use two negative adverbs in the same sentence? becouse my teacher told me that my sentence was wrong for using both of them.

Two negatives tend to indicate a positive.

"He isn't a non-reader." can equal "He is a reader."

Using two negative adverbs in the same sentence can result in a double negative, which can lead to confusion or misinterpretation. In standard English grammar, double negatives cancel each other out and create a positive meaning. This means that the intended negative meaning may become unclear or even reversed.

To understand why you shouldn't use two negative adverbs in the same sentence, let's break down the logic behind it. Adverbs modify verbs, adjectives, or other adverbs. Negative adverbs, such as "never," "no," "not," and "nowhere," convey a negative sense or deny something.

When you use two negative adverbs together, the negative elements compound each other, potentially creating a double negative. For example, consider the sentence: "I can't hardly find it." The negative adverbs "can't" and "hardly" both deny or express a negative sense. However, when combined, they create confusion because "can't hardly" is effectively a double negative.

To fix this, you can choose one negative adverb and rephrase the sentence using only one negative element. For instance, you could say: "I can hardly find it" or "I can't find it." Each of these alternatives conveys a clearer meaning without the confusion caused by using two negative adverbs together.

Remember that language rules can vary based on context, dialects, or informal speech. However, in formal written English or standard grammar usage, it is generally recommended to avoid using double negatives for clarity and effective communication.