optional

optional — adjective

1. available only if someone decides to include it or do it, rather than because a

1.形容詞B2
釋義

available only if someone decides to include it or do it, rather than because a rule says it is needed

例句

Students can join the museum trip, but the visit is optional.

pattern: be optional

The hotel charged extra for optional breakfast on the second day.

collocation: optional breakfast

同義詞
  • voluntary

    often used when a person freely chooses to do something

  • elective

    used especially for school subjects or some medical treatment choices

  • extra

    more informal and often used for added features or services

反義詞
  • compulsory

    states that a rule requires it

  • mandatory

    more formal and common in rules, law, and official instructions

  • required

    the broad everyday opposite

文法句型

be optional

optional extra

optional course

用法筆記

Often used after be and commonly applied to classes, fees, extras, trips, and parts of a form. Distinguish from possible, which is about what may happen, not about a person's choice.

常見錯誤

❌Rain tomorrow is optional.
✅Going tomorrow is optional.
💡optional describes a choice someone can make, not an event that may or may not happen.