Whatever you decide, I'll support you (C1 Grammar)
Use whatever (anything that), whoever (anyone who), or whichever (any one that) to fold two ideas into one word. They already include the thing they point to, so don't add "the thing" or a separate what / who. Notice the emphasis: whatever you decide means "no matter what" — it stays open to any choice, unlike what you decide, which points to one specific thing.
whatever / whoever / whichever: anything that, anyone who
Anything that you decide, I will support. → Whatever you decide, I will support.
Anyone who calls should leave a message. → Whoever calls should leave a message.
Choose any option that suits you. → Choose whichever option suits you.
Not "Whatever you will decide, I'll support you." — say "Whatever you decide, I'll support you.". Use the present tense after whatever, not will — English uses the present for future time here.
Try it: Anyone who finishes first wins the prize. Fold it into one word starting with Whoever. (Leave out the words you don't need.) Answer: Whoever finishes first wins the prize. — Whoever already means anyone who, so the whole idea folds into Whoever finishes first wins the prize. "Anyone who" repeats what Whoever already says, so it is left out. One word carries both parts.
what = the thing that
What can mean "the thing that" and act as the subject or object of the sentence: "What concerns me is the budget" = "the thing that concerns me is the budget". Because what already means "the thing that", don't write "the thing what". Opening with What also reshapes the emphasis: it treats the What-half as ground already agreed and puts the news after is, so "What concerns me is the budget" lands harder than "The budget concerns me". Because the opening half is taken as shared, the move fits a discussion already under way better than a cold opening.
The thing that concerns me is the budget. → What concerns me is the budget.
I'll do the thing that I can. → I'll do what I can.
The thing that she said was surprising. → What she said was surprising.
Not "The thing what concerns me is the budget." — say "What concerns me is the budget.". What already means "the thing that", so don't add "the thing".
Try it: The thing that matters is the result. Start with What to mean "the thing that". (Leave out the words you don't need.) Answer: What matters is the result. — What already means the thing that, so the sentence opens cleanly: What matters is the result. "The thing that" repeats the meaning What already carries, so it is left out. One word does the job of three.
quantifier + of whom / of which: joining detail formally
Quantifier + of + whom / which folds a second sentence about people or things you've just named into the first one — no full stop needed. Use whom for people and which for things after of: "...200 participants, the majority of whom were students." Common quantifiers here are most / many / some / all / none / several / both / half / the majority. Set the add-on off with a comma. This is a formal, written pattern — reach for it in essays, reports and reviews; in everyday speech you'd more likely just start a new sentence: "...most of them were students."
The study had 200 participants. Most of them were students. → The study had 200 participants, most of whom were students.
She interviewed ten experts. Several of them disagreed. → She interviewed ten experts, several of whom disagreed.
He listed three reasons. None of them convinced me. → He listed three reasons, none of which convinced me.
Not "The study had 200 participants, the majority of who were students." — say "The study had 200 participants, the majority of whom were students.". This pattern belongs to formal written English, and there whom is the expected form after of. Of who reads as an error to an editor, so use whom whenever you use this structure.
Try it: The study had 200 participants. Most of them were students. After of, use whom. Build the formal add-on. (Leave out the word you don't need.) Answer: The study had 200 participants, the majority of whom were students. — After of, the form this written pattern expects is whom: the majority of whom were students. "Who" is what you would hear in speech, but here it reads as an error, so it is left out. The phrase joins extra detail onto the main idea without starting a new sentence.