Hi, You're pretty close. "It's either this or that" is correct. Also, "Whether you like it or not" is also correct. The other two options, however, sound pretty odd. You would be understood, but it would mark you as a non-native. There is a toss-off phrase "Either-or" or "Either/or" that people use often when they have no opinion on something. "Do you want a Coke or a Pepsi?" "Either-or." Meaning: they are the same to me; I don't care. The point being, either is paired with two specific options, from which you have to pick, and this is what is being asked or commented on. This OR that, just like you said. "Either you want to watch basketball, or you want to watch racing." "Either you are hot, or you are cold." You are only presented with two choices. The "either-or" pairing may help you remember it, and it will definitely help you sound more native. Next, whether. "Whether" in "whether you like it or not," could easily be replaced with the phrase "I don't care if...." "Whether you like it or not, we are watching basketball." "I don't care if you are hot; I am getting a blanket." "Whether" basically tells the hearer that the decision has been made. "Regardless" is another word you could insert, and perhaps makes the point better. "Regardless of if you like it or not, we have to go buy milk." (This sentence is a bit clunky, but I'm leaving it that way to show the connection. Obviously this is long-winded, but examples help me quite a bit. The short version is, "Either this or that" presents the listener with an option. "Whether you like it or not" takes away the listeners choice. Granted, this isn't 100% across the board, but with these two phrases, that's the major difference. If you want to stick with "either" in phrase two, just specify the Or option. "Either you like it OR you don't like it."

Not correct. Sorry. Find out whether it is true. Find out whether it is this or whether it is that. Whether is conditional on being true, not a choice between items. . I don't know whether you like it . Can't use either here, either, sorry.