1. Restroom vs. lounge: A lounge is a room where you will find a sofa, comfortable chairs, and most likely a TV. If you get to an airport early, generally you can wait in a lounge before you board a plane. A restroom is the same as a toilet and does not mean a place to rest and relax in. If you said that you waited in the restroom for one of your friends, then it would sound a little weird!!!
2. Late vs lately: This is a classic Konglish mistake and one that is easily made. Many second language speakers seem to think that "lately" means "very late," but this is not the meaning. If you have arrived somewhere late, it means that you have not arrived on time. You have arrived after a time that has been agreed upon. If something has started late, it means that an event has started past the time that it was advertised to begin.
The meaning of "lately" on the other hand, is not at all connected with "late." "Lately" means "recently." If you used the sentence ? "I went lately to the English class," it would mean that you arrived recently at the English class and the sentence does not make sense. It would be better to say, "I arrived late for the class." You could, however, say, "I have not attended the class lately." The second situation, of course, has far more serious consequences than the first one.
3. One-piece vs. dress: You might have heard the phrases one-piece, two-piece or even three-piece if you were at KFC. A one-piece is actually a dress. Native speakers of English would not normally say "one-piece" to refer to chicken. We would order one piece of chicken or two pieces. We might, however, use "one-piece" or "two-piece" to describe clothing. Generally a two-piece refers to a suit, which means a skirt and jacket, or a pair of pants and jacket. A three-piece would also have a vest. We might use "one-piece" for a type of jumpsuit or coverall worn by pilots or to mean a bathing suit of a certain type.
4. Cup vs. glass: Our final distinction is between cup and glass. Generally we would not say a "cup of beer." Although there is no rule, it is easier to put the two into the following categories. Cups are for hot drinks, i.e. coffee, tea or hot chocolate and glasses are for cold drinks, i.e. beer, wine, or soda. If you want to talk about soju, you can say a "shot of soju," as generally the glasses for these kinds of alcoholic drinks are small.
We hope that you will use the English terms in your writing, and that this will help improve your spoken English.