know which is which

To be able to identify or distinguish two similar or identical people or things. Tom and his twin always dress so similarly that I never know which is which. I know that the two formats look very much alike, but you really ought to know which is which by this point.

know which is which

and tell which is which

to be able to distinguish one person or thing from another person or thing. I have an old one and a new one, but I don't know which is which. I know that Bill and Bob are twins, but I can't tell which is which.

词组	know which is which
释义	know which is which know which is which To be able to identify or distinguish two similar or identical people or things. Tom and his twin always dress so similarly that I never know which is which. I know that the two formats look very much alike, but you really ought to know which is which by this point. See also: know Farlex Dictionary of Idioms. know which is which and tell which is which to be able to distinguish one person or thing from another person or thing. I have an old one and a new one, but I don't know which is which. I know that Bill and Bob are twins, but I can't tell which is which. See also: know McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. See also: tell which is which which is which tell (someone or something) apart tell apart tell people or things apart tell things apart keep (two or more people) straight (in one's mind/head) keep people straight discriminate between discriminate between (someone or something)
随便看	a shouting match a show of force a show of hands a shrinking violet (as) hungry as a bear (as) hungry as a hunter a shut mouth catches no flies Asia aside aside from as I expected As if! as if as if/as though as if I care As if I care! as if (one) owns the place as if (one's) life depends on it as if someone owns the place as if that were not enough as if there's no tomorrow as if there was no tomorrow as if there was/were no tomorrow as if the sun shines out (one's) backside as/if/when the spirit moves you