Answer:
Here are the sentences changed into negative sentences(the 2nd ones are negative.)
I have finished my work.
I haven't finished my work.
Ram passed the exam.
Ram didn't pass the exam.
The doctor gave me an apple.
The doctor didn't give me an apple.
I finished my homework in one day.
I didn't finish my homework in one day.
He goes to school at 7 o'clock in morning.
He does not go to school at 7 o'clock in morning.
My friend have promised me.
My friend haven't promised me.
Hope this helps, have a great day/night, and stay safe!