The continuous tenses: रहा है and रहा था

The present continuous says what is happening right now: I'm speaking, it's raining. Take the verb without -ना (-naa), add रहा (rahaa), रही (rahee) or रहे (rahe), and finish with हूँ, हो, है or हैं (hoon, ho, hai, hain). रहा agrees with the subject like an adjective: -आ for a man or a masculine thing, -ई for a woman or a feminine thing, singular or plural, and -ए for men with तुम, आप, हम, वे and for masculine plurals.

The continuous tenses never take ने (ne), even with an object.

Besides “right now”, the present continuous is used for plans that are already arranged, as in English: मैं कल दिल्ली जा रहा हूँ (main kal Dillee jaa rahaa hoon), I'm going to Delhi tomorrow. It's also used for something already on its way: कोई आ रहा है (koee aa rahaa hai), someone is coming.

For “not”, put नहीं (naheen) before the verb. The final है (hai) is often kept, but you'll hear it dropped too: एसी नहीं चल रहा (esee naheen chal rahaa), the AC isn't working.

For something that started in the past and is still going on, Hindi uses the present continuous with से (se, since, for). English says “have been doing”: मैं दो साल से हिंदी सीख रहा हूँ (main do saal se Hindee seekh rahaa hoon), I've been learning Hindi for two years.

With states, the plain present is enough: मुझे कल से बुख़ार है (mujhe kal se bukhaar hai), I've had a fever since yesterday. For something that is over, use the simple past without से: मैंने वहाँ चार साल काम किया (mainne vahaan chaar saal kaam kiyaa), I worked there for four years.

To say what was going on at some moment in the past, replace the final हूँ, हो, है or हैं with था (thaa), थी (thee), थे (the) or थीं (theen): मैं बात कर रहा था (main baat kar rahaa thaa), I was talking. It often sets the scene for something that happened: हम घूम रहे थे, और फिर बारिश हुई (ham ghoom rahe the, aur phir baarish huee), we were walking around, and then it rained.