Is simple past used both for ’Kiya’ and ‘Kiya tha’?
I am sorry I passed out [mujhe maaf karna meri aankh lg gyi thi]
I went to cinema yesterday [mai kal cinema gya tha]
She wrote a letter to her father [usne apne pita ko ek khat likha]
Did he eat the dinner? [Kya usne khana khaya?]
I don't understand why in some sentences ‘tha’ is omitted while in some it is not
The ones with no 'tha' are in the simple past tense and those with 'tha' are in the past perfect tense.
So, the translations of 'मेरी आँख लग गयी थीं' and 'मैं कल सिनेमा गया था' are 'I had passed out' and 'I had gone to the cinema yesterday'. 'I passed out' and 'I went to the cinema' would be 'मेरी आँख लग गयीं' and 'मैं सिनेमा गया'.
Note: 'Cinema' is not used as 'movie theatre' in India like in these sentences (both in Indian English and Hindi). Instead, it would refer to the movies themselves. A theatre would be 'Cinema ghar' in Hindi.
Also, 'आँख लग गयी' is 'fell asleep'. So, it can be a translation of 'passed out' only in certain contexts.
The past perfect is used when you are talking about an event that happened before a certain reference point in the past.
(This reference point need not be within the sentence but may also be given through context. In English, we tend to steer clear of the past perfect when the reference point is not explicitly within the sentence - sometimes even when it is because we don't want to use the infamous 'had had'. This is not so in Hindi.)
In the sentence 'मैंने उम्मीद नहीं की थी कि तू ऐसा करेगा' (Note: करी is a colloquialism. Actual form is की), the act of expecting is happening before the reference point which is when the other person did whatever he did. Literally, it would be 'I had not expected you to do something like this'.
On the other hand, if the sentences are not constrained with such reference points (when telling a story for instance where you are constantly shifting reference), you can say something like मैंने किसी से कोई उम्मीद नहीं की (I did not expect anything from anyone) that is in the simple past tense.
When I arrived at the cinema, the movie had already started - जब मैं सिनेमाघर पहुँचा, फ़िल्म शुरू हो चुकी थी. The first clause is in the simple past and establishes a reference. The second clause is in the past perfect because it takes place before the reference.