Someone?

Singular, as expected
d

The verb that directly follows "someone" should be in the singular:

Someone is trying to deceive me.

However, the plural pronouns/possessive determiners/etc. ('they/them/their/etc.') have been used after words like "someone" for centuries (when the gender of a person is unknown):

She doesn't like it when someone is trying to i

kunsusukiBecause my teacher said that we use the plural??

Hard to believe!
Can you give an example of what your teacher would say??

Well, here is the example: "It's quite common to hear someone complain that their memory is not as good as it used to be or that the more things they try to remember, the more quickly they seem to forget."

kunsusukiWell, here is the example: "It's quite common to hear someone complain that their memory is not as good as it used to be or that the more things they try to remember, the more quickly they seem to forget."

Yes, as I said earlier, this use of 'they/their/them' has a long history in the English language. Some grammarians and prescriptivists still object

In addition to the comment above, it's worth noting that this use of 'they' doesn't have the feeling of plurality.
d

Here you are talking about the pronoun or the determiner that follows "someone" but I'm talking about the verb it follows.

kunsusukiHere you are talking about the pronoun or the determiner that follows "someone" but I'm talking about the verb it follows.

There is nothing wrong with the verb in the sentence you quote. Verbs of perception (such as 'hear', 'see', 'watch') are often followed by the base form of another verb (or the -ing form), so the grammatical number of the p

kunsusuki Hi everyone! well do we use the plural or the singular after someone? Because my teacher said that we use the plural??

Hi kunsusuki,
I'm glad you have provided the following example:
"It's quite common to hear someone complain that their memory is not as good as it used to be . . . . "

To avoid confusion, it's worth pointing out the noun-verb matchings here:-

"It's quite common to hear someone complain that their memory is not as good as it used to be . . . . "

someone complain - singu