The object of "for" is the whole of the following clause, and not just the relative pronoun, and that clause should follow the proper rules of subject-verb-object grammar.

Learn to make sure the subject of a sentence matches the verb correctly.

A sentence in the active voice typically has the formation of Subject Verb Object SVO. The verb needs to be in agreement with the subject for proper grammar formation.

Which is why I actually enjoy knowing about object complements. Like subjects, objects, verbs and modifiers, object complements can be an integral part of a sentence.

Just by getting Katie and Kevin out of the picture, we see clearly that these sentences call for an object, not a subject. That doesn’t change just because Katie or Kevin shows up.

In sentences in the active voice, the subject occupies the initial position while it is at or towards the end of the clause in the passive.

WE all know that when a sentence uses a transitive verb as the operative verb, it's absolutely necessary for the subject to take a direct object and to act on it: "The woman spurned her suitor ...

Can language exist without grammar? Children learn these structures very quickly, before they know what the terms subject, object and verb actually mean! This had led some language professors to ...

So-called Al-Sayyid Bedouin Sign Language also builds sentences around a subject-object-verb construction. “Consistent word order appears early in a new sign language,” she says.