Compound What?
Here’s a sentence. Is it right or wrong? (Maybe I should say, “Is the grammar correct?”)
While Subversion is still primarily a copy-modify-merge system, it still recognizes the need to lock an occasional file and thus provide mechanisms for this.
I saw this in some instructional material for a file management program named Subversion. (Yes, the first word should be “Although,” but that’s not the thing I’m thinking about.) What about “provide”? Shouldn’t it be “provides” to go with “recognizes”? After all, the subject of the sentence is “it,” right?
Well, yes, the word could be “provides” to go with the singular subject. But the sentence is correct nonetheless! Can you tell why?
Because instead of the sentence having a compound predicate, it has a compound infinitive! It’s “to lock” and “to provide.” That “to” serves both words.
This is one of those (rare) cases where no matter which you do, you’re right!
This comes from the October 2018 SAT, and is represented as a correct sentence:
Some studies have also found that students who do community service are more likely to volunteer as adults, and thus affect society positively over the course of many years.
I cannot name a comma rule that would require its appearance after an independent clause and before a coordinating conjunction when the conjunction joins the infinitive components “volunteer” and “affect.”