Which one should I use? "OF IT" or "OF WHICH" [closed]
Solution 1:
Technically, if you use of it, you have a run-on sentence: both "I bought a watermelon from the market" and "half of it was rotten" are complete sentences, so you are joining two sentences with a comma splice, which gives a run-on sentence.
On the other hand, half of which is really quite formal English, and for everyday writing, most people don't worry too much about run-on sentences (and you can't hear the difference between a comma and a semicolon, so in speech it's not even a run-on sentence). So for most occasions, of it might actually be better.