We are writing school assignment __________ black ink.
We are writing school assignment __________ black ink.
Explanation
We are writing school assignments in black ink.
ہم کالی سیاہی سے اسکول کی تفویض لکھ رہے ہیں۔
When we use ( pen) to write, we use ( ink) instead of (pen).
Then we have to use the preposition ( in ) but not ( with)