मैंने सुबह खिड़की खोली, लेकिन मेरे भाई ने दरवाज़ा नहीं खोला।

I

Breakdown of मैंने सुबह खिड़की खोली, लेकिन मेरे भाई ने दरवाज़ा नहीं खोला।

• मेरा: my
• भाई: brother
• नहीं: not

Questions & Answers about मैंने सुबह खिड़की खोली, लेकिन मेरे भाई ने दरवाज़ा नहीं खोला।

Why is it मैंने instead of just मैं?

Because Hindi often uses ने with the subject in the perfective past when the verb is transitive (that is, it takes a direct object).

Here, खिड़की खोली means opened the window, and the action is completed, so Hindi uses:

• मैंने = I
  • ergative marker ने

Compare:

• मैं खिड़की खोलता हूँ = I open / I am opening the window
• मैंने खिड़की खोली = I opened the window

So ने is a very common marker in past completed actions with transitive verbs.

Why does मेरे भाई also take ने?

For the same reason: भाई is also the subject of a completed transitive action.

In the second clause:

• मेरे भाई ने दरवाज़ा नहीं खोला
• My brother did not open the door

Since open is a transitive verb and the action is in the perfective past, ने is used again with the subject.

Each clause has its own subject and verb, so each clause needs its own grammar.

Why is it खोली in the first clause but खोला in the second?

Because the verb agrees with the direct object here, not with the subject.

Since the subjects have , the perfective verb usually agrees with the direct object if that object has no .