"I loved the drawings, they were so real."
Personally, I feel there's nothing wrong with the sentence. It's a question that appeared in an exam. We are supposed to correct the sentence.
Solution says : Replace 'they' by 'which'. 'The drawings' is a relative clause so we need a relative pronoun for it.
but that doesn't make any sense to me logically. Can somebody explain?
The teacher's answer is correct. A sentence expresses a complete thought. The original sentence is two complete sentences separated by a comma, which is grammatically incorrect. It's two thoughts jammed together. As JK notes, you can add a conjunction. You can change the comma to a period, which gives you two complete (and correct) sentences. You can reword and rearrange the two thoughts in any number of ways.
The original sentence isn't completely wrong. You would probably say that in conversation, which is okay because it's informal (also nobody says comma or period out loud). The exam, however, was about formal English. There are rules in language because, without them, we couldn't understand each other.
First of all, I hope you can learn the use of conjunctions.
"I loved the drawings, they were so real." can be divided by two sentences. So if you want to joint two sentences in English grammar, you should add a conjunction between these. For example:
"I loved the drawings, which were so real". There is only one sentence.
or "I love the drawings, and they were so real". It's two sentence jointed by a conjunction which is "and".
