"as if" structure

[Nat093]

Hello. I've learnt that:

"when the main clause is in the past tense, we do not use a past perfect after as if to show that a comparison is unreal. Instead we use a simple past in both clauses.
e.g. She looked as if she knew everything, but she didn’t."

And my question is: if I wanted to emphasise that the comparison was real (I was sure that she knew everything), which tense should I use after “as if”?

 

[probus]

Not sure I understand the question. I can't think of any context or intended meaning in which one would use anything but "knew" after "she looked like." You could say "She looked like she knew everything, and it was obvious that she did", or "... and I was certain she did."

 

[Raymott]

Of course you can use the past perfect if that's your meaning.
"She looked as if she had already heard the news before I told her."
If there's any rule, it's "Don't use a certain tense if what you mean is better expressed in another tense."

 

[Matthew Wai]

... (I was sure that she knew everything), which tense should I use after “as if”?

As the speaker was sure about that, was it proper to use 'as if', which might suggest uncertainty?

Not a teacher.

 

[Roman55]

I am not a teacher.

The speaker might be sure and still be mistaken.

 

[Matthew Wai]

If the speaker thought it could be a mistake, how could s/he be sure?

Not a teacher.

 

[Roman55]

I am not a teacher.

Being sure is subjective.

You can be convinced of something and still be wrong. There is no contradiction here.