useful

useful — adjective

1. able to help you do something, solve a problem, or achieve a result in an effect

1.形容詞A2
釋義

able to help you do something, solve a problem, or achieve a result in an effective way — for example, a useful tool, a useful piece of advice, or a useful skill.

例句

A good dictionary is useful when you are learning a new language.

useful + when-clause: describing a situation

Linh found several useful tips for growing vegetables in a small balcony garden.

useful before a noun (attributive)

同義詞
  • helpful

    Can be used for both people and things; more personal and friendly tone.

  • practical

    Emphasises effectiveness in real situations; a practical tool works well for everyday tasks.

  • handy

    Informal; suggests something is convenient and easy to use, often small or portable.

  • valuable

    Stronger than 'useful'; suggests high worth or importance, not just helpfulness.

反義詞
  • useless

    The most direct opposite; not serving any purpose or achieving any result.

  • pointless

    Emphasises a lack of purpose or reason; suggests effort would be wasted.

文法句型

useful + for + noun/gerund

useful + to + infinitive

it is useful + to + infinitive

useful + to + person

用法筆記

Can be used both before a noun (a useful gadget) and after a linking verb (this tool is useful). The structure 'it is useful + to-infinitive' is very common for giving advice or suggestions.

常見錯誤

❌She is a very useful person in the office.
✅She is a very helpful person in the office.
💡'useful' is typically used for objects, tools, or abstract things (advice, information), not for people's helpful character. Use 'helpful' for a person's willingness to assist.

2. still able to be used or to produce good results, especially when describing how

2.形容詞B2
釋義

still able to be used or to produce good results, especially when describing how long something remains functional or productive — for example, the useful life of a machine, or making yourself useful by doing helpful tasks.

例句

The architect estimated the useful life of the building at fifty years.

collocation: useful life

Defne made herself useful by helping the team pack up chairs after the school concert.

phrase: make oneself useful

同義詞
  • serviceable

    More technical; suggests something is in good enough condition to be used, often after repairs or wear.

  • functional

    Focuses on whether something works rather than how well it works.

文法句型

useful + life / years / days

make + oneself + useful

用法筆記

This sense often appears in the fixed expression 'useful life' (the expected period something works properly) and the phrase 'make yourself useful' (a friendly way to ask someone to help).