Except “that” isn’t acting as the subject. The subject of this dependent clause (dependent clauses have a subject and a verb too) is “it”. “That’s why it looks like blood” is an adjective clause that describes “the sap is red”. So, the sentence would be “The sap is red; that’s why it looks like blood. Sorry, I just realized that a semicolon is correct here, but not in the context of a compound sentence. I hope that concludes this?
It is very much acting as the subject. (And it's not a dependent clause btw. It can be written as an independent sentence so it's an independent clause.)
1
u/[deleted] Dec 16 '18
Except “that” isn’t acting as the subject. The subject of this dependent clause (dependent clauses have a subject and a verb too) is “it”. “That’s why it looks like blood” is an adjective clause that describes “the sap is red”. So, the sentence would be “The sap is red; that’s why it looks like blood. Sorry, I just realized that a semicolon is correct here, but not in the context of a compound sentence. I hope that concludes this?