I know (a) Tom who lives in the States, but I don't know (a) Tom who lives in China

[tijay1]

Could you please help me to understand the difference between the following sentences:
a. I know Tom who lives in the States, but I don't know Tom who lives in China.
b. I know a Tom who lives in the States, but I don't know a Tom who lives in China.
(The source of these examples is https://www.usingenglish.com/forum/threads/a-tom-who-lives-in-the-states.300733/#post-1921842 )

 

[5jj]

a. I know Tom who lives in the States, but I don't know Tom who lives in China.
I don't find this natural.

b. I know a Tom who lives in the States, but I don't know a Tom who lives in China.
= I somebody called Tom who lives in the States, but I don't know anybody called Tom who lives in China.

c. I know the Tom who lives in the States, but I don't know the Tom who lives in China.
= Of the two people called Tom previously referred to, I know the one who lives in the States, but I don't know the one who lives in China.

 

[tijay1]

a. I know Tom who lives in the States, but I don't know Tom who lives in China.
I don't find this natural.

b. I know a Tom who lives in the States, but I don't know a Tom who lives in China.
= I somebody called Tom who lives in the States, but I don't know anybody called Tom who lives in China.

c. I know the Tom who lives in the States, but I don't know the Tom who lives in China.
= Of the two people called Tom previously referred to, I know the one who lives in the States, but I don't know the one who lives in China.

Thank you for your answer.
How about the folowing three versions:
d. I know _ Tom who lives in the States.
e. I know the Tom who lives in the States.
f. I know a Tom who lives in the States.
In what kind of situations are they possible?

 

[jutfrank]

Ah, I just answered in the other thread before I saw this one.

Mods: Should I move my post to here?

 

[emsr2d2]

Ah, I just answered in the other thread before I saw this one.
Mods: Should I move my post to here?

I think that's a good idea. If no one had responded to this thread, I would have deleted the thread and left the original question and your response in the other thread.

 

[emsr2d2]

Thank you for your answer. How about the following three versions?

d. I know _ Tom who lives in the States.
e. I know the Tom who lives in the States.
f. I know a Tom who lives in the States.

In what kind of situations are they possible?

I assume the underscore in d is meant to reinforce the fact that you haven't put an article before "Tom". If so, it wasn't necessary. If you re-read 5jj's response, I think you'll find the answer.