What is the most useful english word or expression??

The F word. It's so versatile.

It's a language bro, you can't have a singular most useful word or expression.

Do you mean common expressions that are useful in the day-to-day? Or specific words to express yourself?

Instead of saying "goodbye", you say "Hasta la vista, baby!"

Please thank you and you’re welcome

Here are the most useful phrases in a relationship context: "You're absolutely right" "I completely agree" "\[insert partner's coworker name\] was definitely being unreasonable"

"Damn, that's crazy" said however many times it takes to end the conversation "I don't speak English" great for dealing with pesky solicitors and salesmen "Please and thank you" always good to mind your manners

“Is there a customer bathroom I can use?” or “may I use your WiFi?”

* Hello * Thank you * Sorry

"Point to bathroom"

No

"What the fuck?"

No

Where, how and when.

Oooh! I know this one: 1. What is this/that? 2. How do you say this/that? 3. I don't understand this/that. These are the most useful phrases in any language.

“We’re all mammals here,” because it applies to most people and their cats.

Sorry - please - thank you

"Okay"

The, be, to, of, and, a, in, that, have, I, it, for, not, on, with, he, as, you, do, at. These are among the most important words in the English language. They are—literally—the 20 most-used words in the language. Communicating without them would be nearly impossible, or would make communication nearly incomprehensible.

“I am sorry; please forgive me”. This is one of the hardest things to say in English, and one of the most necessary.

There isn’t a single most useful aspect of the English language, but I can highlight one particularly valuable feature: emphasis. Emphasis plays a crucial role in conveying meaning in English. The same sentence can take on different interpretations depending on which word is stressed. Here are some examples: > I never said she stole my money. (Implies that someone else made the claim.) > I _never_ said she stole my money. (Emphasizes that the statement was never made.) > I never _said_ she stole my money. (Suggests that the idea may have been implied but not stated directly.) > I never said _she_ stole my money. (Indicates that someone else might have stolen it.) > I never said she _stole_ my money. (Implies she may have taken it in some other way.) > I never said she stole _my_ money. (Suggests that it may have been someone else’s money.) This flexibility allows you to convey subtle nuances without changing the words themselves, which can be a powerful tool.

I'm particularly fond of trogladyte and luddite.

You can't get far in any language with only three terms -- imagine trying to do so in your native tongue! So if I were crazily restricted like that, I'd teach a few that might reduce problems or generate goodwill. "Sorry, I don't speak English; do you speak \[language(s) I do know\]?" "Thank you." "Where is the toilet?"