разве

1. Function and Nuance
Разве is fundamentally an interrogative particle (вопросительная частица) that also functions as a modal particle used to express doubt, surprise, or indignation. It indicates that the speaker had a specific expectation that is now being challenged by new information. It often expects a negative answer to a positive question (e.g., "Is it really...?" implying "I thought it wasn't"). Note that the particle разве itself does not trigger a comma, though one may follow it if required by other sentence structures (such as a vocative).

2. Sentence Position

• Initial Position: Most commonly, it starts the sentence: Разве трава синяя? (Wait, is the grass really blue?).
• Mid-sentence: It can be placed before a specific word to focus the doubt on the element that follows it: Трава разве синяя? (Is the grass really blue?).

3. The Negative Question Pattern
When used in the pattern разве не, the speaker typically expects a positive answer. It functions like the English "Surely...?" or "Isn't it...?".
Разве тут не все счастливы? (Surely everyone here is happy?).

4. Rhetorical Questions and Indignation
Разве is frequently used in rhetorical questions to emphasize a point or express indignation. A highly common core usage is разве можно (is it really okay/permissible?), which strongly implies that an action is completely unacceptable (e.g., Разве можно так делать? - How can one do that?).

5. Hesitant Suggestions and Exceptions
To introduce a tentative suggestion or an exception (meaning "unless" or "except for"), the fixed phrases разве что, разве только, and разве лишь are used. While some older sources might tag these as colloquial, разве что is widely used in neutral, standard written Russian and is not strictly colloquial. Note that разве что is not an introductory word (вводное слово) and is therefore not isolated with commas when used within a single clause (e.g., Я люблю разве что комедии. - I only like comedies, perhaps). However, when it acts as a subordinating conjunction connecting two full clauses, a comma must precede the clause it introduces: Я не пойду туда, разве что ты пойдёшь со мной. (I won't go there, unless you go with me).
Разве что сходить в магазин... (Maybe I should go to the store... / Unless I go to the store...). In colloquial speech, разве + infinitive can be used to muse about a course of action (e.g., Разве пойти спать? - Maybe I should just go to bed?). Additionally, in colloquial speech, разве can be used in declarative sentences with conjugated verbs to mean "maybe/perhaps" or "the only possibility is..." (e.g., Гостей не будет, дедушка разве зайдёт. - There won't be guests, maybe just grandpa will drop by). In colloquial contexts, разве can be used alone as a conjunction meaning "unless" (e.g., Я приду, разве заболею - I will come, unless I get sick). Furthermore, the pattern разве что не + verb is used in declarative sentences to mean "practically [doing X]" or "doing everything but [X]" (e.g., Он разве что не плакал. - He was practically crying / He did everything but cry).

6. Comparison with неужели
While both express surprise, неужели is much stronger and more emotional, often implying total disbelief or shock. Разве is more about checking a logical contradiction or a mild surprise regarding an assumption. Both can be used as standalone one-word responses: Разве? expresses mild doubt ("Really?"), while Неужели! expresses shock ("No way!").

7. Indirect Questions
English speakers often mistakenly use разве to translate "if" or "whether" in indirect questions. However, разве cannot be used this way. For neutral indirect questions, you must use the particle ли (e.g., Он спросил, готов ли я. - He asked if I was ready).

8. Intonation
Because разве is a modal/interrogative particle, it relies heavily on spoken intonation. In speech, questions with разве typically use Intonation Construction 3 (IK-3), where the speaker's voice rises sharply on the specific word being questioned.