We looked everywhere but ...

[Freeguy]

We looked everywhere but the intruder was nowhere ...... .

1. having seen
2. seen
3. that seen
4. to be seen


What's wrong with no.4?

 

[5jj]

We looked everywhere but the intruder was nowhere ...... .

1. having seen
2. seen
3. that seen
4. to be seen


What's wrong with no.4?

Nothing. It's the correct answer.

 

[Freeguy]

Dear 5jj, thanks for your answer. The answer key has chosen No.2 as a correct one. So I was in a quandary. What's wrong with No.2

 

[Raymott]

Dear 5jj, thanks for your answer. The answer key has chosen No.2 as a correct one. So I was in a quandary. What's wrong with No.2

The key is wrong. "The intruder was nowhere seen" is unnatural.

 

[SoothingDave]

"Nowhere to be found" is the expression I would expect to see.

 

[emsr2d2]

Nowhere to be seen/found both work for me.

 

[anhnha]

How about this one?
The intruder was seen nowhere.

 

[Rover_KE]

How about this one?
The intruder was seen nowhere.

Unnatural.

 

[anhnha]

I wonder if the statement "I see him nowhere." with the intended meaning as below is natural or not. It is the form that my teacher usually uses.
"I see him nowhere." with the meaning "I don't see him anywhere."

 

[5jj]

"I see him nowhere" is not very natural. I'd say "I can't see him anywhere".