anyone would guess you wrote it

In a classroom, one student (A) to another (B):

A: I'm surprised! How did you know I wrote it on the board? (The writing is still there on the board)
B1: It's pretty simple. Looking at the handwriting, anyone could guess you wrote it. (Guessing about the present)
B2: It's pretty simple. Looking at the handwriting, anyone would guess you wrote it. (Guessing about the present)

Is the verb "wrote" used in a hypothetical/unreal sense in B1 and B2, just like the modal verbs "could" and "would"? Or does it have a real past meaning, as it has in the statement of A: How did you know I wrote it on the board?

Note: the context and sentences are all mine.

How can it be hypothetical? The writing is there on the board!

teechar said:

How can it be hypothetical? The writing is there on the board!

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Would past perfect tense be alright in the context above?

B1: It's pretty simple. Looking at the handwriting, anyone could guess you had written it.

B2: It's pretty simple. Looking at the handwriting, anyone would guess you had written it.

No, that would be entirely unnatural.

NAL123 said:

Would past perfect tense be alright in the context above?

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No.

The original sentence is equivalent to saying 'It's obvious that you wrote it.' That's about a real past action, as you say. The past simple is the right tense to say what you mean.

jutfrank said:

No.

The original sentence is equivalent to saying 'It's obvious that you wrote it.' That's about a real past action, as you say. The past simple is the right tense to say what you mean.

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In the given context, can I also say the following:

B3: It's pretty simple. Looking at the handwriting, anyone could've guessed you wrote it. (Guessing about the past)

B4: It's pretty simple. Looking at the handwriting, anyone would've guessed you wrote it. (Guessing about the past)

No. Stay with your original B2 sentence. Alternatively:

From the handwriting, it's obvious that you wrote it.

jutfrank said:

No. Stay with your original B2 sentence. Alternatively:

From the handwriting, it's obvious that you wrote it.

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Let me change the context a little:

In a classroom, one student (A) to another (B):

A: I'm surprised! How did you know I wrote it on the board? (The writing is not on the board now. Maybe someone erased it, but B had already seen it.)

B3: It's pretty simple. Looking at the handwriting, anyone could've guessed you wrote it. (Guessing about the past)

B4: It's pretty simple. Looking at the handwriting, anyone would've guessed you wrote it. (Guessing about the past)

Are B3 and B4 correct?

We wouldn't use "anyone could/would guess..." in this context. Am I right?