In Russian, the word "должен" is a really important verb. It means "must" or shows that something is necessary. If you're learning Russian, it's essential to know how to use "должен" in different ways. This helps you explain what needs to be done. Let’s break it down!

1. Basic Forms of "должен"

The word "должен" changes based on who you're talking about. Here are the different forms:

• Masculine: должен (he must)
• Feminine: должна (she must)
• Neuter: должно (it must)
• Plural: должны (they must)

Example sentences:

• Он должен прийти.
  (He must come.)

• Она должна учиться больше.
  (She must study more.)

• Это должно быть правильно.
  (This must be correct.)

• Они должны закончить работу.
  (They must finish the work.)

2. Expressing Necessity

"Должен" shows that something is really needed. It tells us that the speaker thinks an action is important and there isn’t really a choice.

Structure

It’s simple to use:

• Subject + "должен" + verb.

For example:

• Я должен изучать русский язык.
  (I must study the Russian language.)

3. Contextual Variations

"Должен" usually shows obligation, but its meaning can change depending on the situation:

• Personal obligation: This means something you feel is your responsibility.
• External authority: This means that rules or other people are telling you to do something.

Examples:

• Я должен заплатить за квартиру.
  (I must pay for the apartment.) - Personal obligation.

• Ты должен следовать правилам.
  (You must follow the rules.) - External authority.

4. Degrees of Necessity

In Russian, you can also show different levels of necessity, just like in English:

• Strong necessity: Use "должен" when you really have no choice.
• Weak necessity: Use "нужно" or "надо," which means it’s a good idea but not required.

Example Comparisons:

• Ты должен одеться потеплее.
  (You must dress warmly.) – strong necessity.

• Тебе нужно одеться потеплее.
  (You need to dress warmly.) – weak necessity.

5. Questions and Negations

To ask questions, you can change the sentence around a bit or switch the subject and the verb:

• Statement: Ты должен прийти.
  (You must come.)

• Question: Ты должен прийти?
  (Must you come?)

To say that something is not necessary, just put "не" before "должен":

• Я не должен идти на встречу.
  (I must not go to the meeting.)

6. Common Expressions with "должен"

Here are some common phrases that use "должен":

• Ты не должен бояться – You must not be afraid.
• Им должно быть стыдно – They should be ashamed.

7. Summary

Modal verbs like "должен" are super important for showing necessity in Russian. Knowing the different forms helps you communicate clearly every day.

Understanding how to use "должен" for your own obligations or for rules set by others can make your Russian conversations better and more detailed.

Try practicing "должен" along with "нужно" and "надо" to really get the hang of talking about what needs to be done in Russian!