- 1. He looks as if he knows the answer. (= He seems to know the answer, and he probably does.)
- 2. He looks as if he knew the answer. (= He seems to know the answer, but he doesn't.)
Can you explain why the different tenses between 1 and 2 would have rendered the different meaning? I quote this from an English website.
I don't think their explanations are very clear, and for #2 I think they are simply wrong.
"He looks as if he knows the answer." This is a shorter way of saying, "He looks as if he
is confident that he knows the answer," or "He looks confident about knowing the answer," or various other ways of saying the same thing.
The problem with the short sentence in the original example is that it leaves out several words. This is not a problem for native speakers, but it may mislead non-natives.
To say, "He looks as if he has been working too hard," expresses the observation that he is sweating, moving slowly, and generally acting exhausted. This is an empirical
observation. But to say, "He looks as if he knows the answer," expresses not an observation but an
assumption. We have no way of knowing whether he actually knows the answer. What we really mean is that his appearance suggests to us that
he believes that he knows the answer. If we agree with this belief, if we also believe that he knows the answer, this is our
assumption.
In other words, this sentence means that he looks
confident about it. This is actually rather sloppy English, but nonetheless we all talk that way
because we understand what we mean.
But the second sentence, "He looks as if he
knew the answer"? That is not just awkward, it's difficult to understand. It says that he has the appearance of a person who
used to know the answer, but has forgotten it. What, exactly, does that person look like? Is he grimacing, grinding his teeth and squinting his eyes in an effort to dredge up a memory that is temporarily lost? If I were actually trying to describe that scene, I would be much more
descriptive, and include the words I just wrote in my preceding sentence.
He looks as if he once knew the answer to this question and is frustrated by his inability to recall it, wracking his brain to extract it from his memories.
A note: "as if" is colloquial English. It's fine in conversation and even in casual writing. But it's more proper to say, "He looks
as though he knows the answer." If you're ever writing a formal paper, be sure and use that wording.