“Antidotes!” said Snape, looking around at them all, his cold black eyes glittering unpleasantly. “You should all have prepared your recipes now. I want you to brew them carefully, and then, we will be selecting someone on whom to test one. . . .”

This is a sentence from Harry Potter and the Goblet of Fire.

What's the meaning of on whom in this context? Could I just omit it?

Thanks in advance.

1 Answer 1


No. You cannot omit it. If you do, the meaning is

select one of you to conduct the experiment.

When you conduct the experiment, you inject the germs into someone else.

When you include “on whom,” the meaning is

select one of you to be the subject of the experiment.

When you are the subject of the experiment, someone else injects the germs into you.

  • Thank you for kindly help! So this is a fixed usage or some kind of grammar structure?
    – hustnzj
    Commented Jun 15, 2022 at 2:05
  • 1
    The verb here, “test,” is being used in the sense of “experiment.” The grammatical form is verb, direct object, preoposition, indirect object. Basic form. “We test the drug on animals before we test it on humans.” Is it “whom” that is causing you questions? Commented Jun 15, 2022 at 7:33
  • 1
    The sense is "We will be selecting someone to test one [of the recipes] on." Commented Jun 15, 2022 at 7:45
  • Jeff, @KateBunting, I didn't know "test sth on sb" before. Thank you both.
    – hustnzj
    Commented Jun 15, 2022 at 8:24

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