Is ''should know'' correct? vs Should Have Known
most of the times I see ''you should've known'' but I wonder if ''should know'' it's correct (in the present tense)

e.g. You should know that this kind of attitudes are unnecessary

should have known - past
should know - present

is it right?

Question

Is ''should know'' correct? vs Should Have Known
most of the times I see ''you should've known'' but I wonder if ''should know'' it's correct (in the present tense)

e.g. You should know that this kind of attitudes are unnecessary

should have known - past
should know - present

is it right?

Answer

"Why were you so rude to him?  You should have known the right thing to say. I am angry with you now."

"If you want to avoid being rude, you should know the right thing to say."

Can you see the difference in usage?