Unit 9 · Modals
Modals & impersonals
Cases already put the person in dative (мне холодно, мне нужно). This unit is how you say allowed / not allowed / need / ought — можно, нельзя, нужно, надо, должен — without copying English can and must. Each lesson: How it works → Tables → Notes → Exceptions → Examples.
Lessons
Lesson 1
можно — allowed
Можно
можно is impersonal: the situation allows it. Who is allowed sits in the dative (мне, тебе, ему). Do not copy English can with я могу when you mean permission.
Lesson 2
нельзя — not allowed
Нельзя
нельзя is the impersonal no: forbidden, or not possible. Same dative person as можно. It is not the same as я не могу (I am unable).
Lesson 3
нужно / надо — need
Нужно, надо
Need is dative + нужно / надо, then an infinitive — not I need to with a nominative I. When you need a thing, нужен / нужна / нужно / нужны agrees with that thing.
Lesson 4
должен — ought
Должен, должна
должен is not impersonal. The person is nominative and the word agrees: я должен, она должна, они должны. Closer to duty / expected to than мне нужно.
Lesson 5
Don’t mix the nos
Не надо и нельзя
English have to / must / can collapses four Russian pictures. The high-stakes split: не надо = no need; нельзя = must not. Also можно vs могу, and мне нужно vs я должен.