What's the difference between "once" and "when"?

Native speaker’s answer

Rebecca

"Once" is used here because the speaker wants to talk about a specific incident or event that occurred in the past. It cannot be replaced with "when" in this context. Ex: Once, I got 100% on my math exam. Ex: Once, I won a gold medal at my track and field competition. Now, in other cases, "once" and "when" are often used interchangeably. The meaning of the two words overlap somewhat and both can be used as conjunctions to mean “as soon as” or “after.” Ex: You can eat once the food arrives. = You can eat when the food arrives. The difference is that "when" is interrogative and is used to introduce questions about time, while "once" refers to the frequency and is usually only one time.

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Popular Q&As

12/10

1
What's "the late" mean?
Good question! "The late" is a polite and respectful way to refer to someone who has died in the last decade or so. Ex: The king of pop, the late Micheal Jackson, was known worldwide. Ex: The late Sarah Walker was quite wise in her ways. => She did things with wisdom

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4
What kind of joke is this?
He is joking here that the person would not be perfect for him if they were actually "perfect", but if they were "co-dependent" and "self-destructive" then they would be the perfect person for him. He says this as a joke because he thinks that he is "co-dependent" and "self-destructive", so if someone else were like that too, then they would be a perfect match.

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What does "salty" mean?
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