In Russian, the verb "быть," which means "to be," is really important for making negative sentences in the present tense. We often leave it out in everyday speech, but knowing when to use it can help make our sentences clearer, especially when we want to express something negative.

Key Grammar Points:

1. Noun Gender and Cases:

   • Masculine: стол (table)
   • Feminine: книга (book)
   • Neuter: окно (window)
   • Cases: The subject of a sentence is usually in the nominative case (who/what the sentence is about), and the object is in the accusative case (who/what is being talked about).

2. Making Negative Sentences:

   • To create a negative sentence, just add "не" before the verb or noun.
   • For example:
     • Affirmative: Он инженер. (He is an engineer.)
     • Negative: Он не инженер. (He is not an engineer.)
   • Remember: After "не," the noun stays the same in gender and case.

3. Adjective Agreement:

   • When using adjectives in negative sentences, they must match the noun in gender, number, and case.
   • For example:
     • Affirmative: Она умная. (She is smart.)
     • Negative: Она не умная. (She is not smart.)

4. Present Tense Verb Conjugation:

   • Regular verbs change form depending on who is doing the action. Here are a couple of examples:
     • Я читаю (I read)
     • Ты читаешь (You read)

5. Asking Questions:

   • You can ask questions by changing your tone or using question words.
   • Here are some examples:
     • Что это? (What is this?)
     • Где ты? (Where are you?)

By understanding these points, you'll become better at making clear and correct sentences in Russian, especially when you want to say something negative.