是個

In a sentence

• 他是個誠實的人。

  He is an honest person.

  In this sentence, "是個" is used to indicate the identity or characteristic of the subject "he", showing a specific trait "honest person".

• 這是一個很好的學習機會。

  This is a great learning opportunity.

  Here, "是一個" highlights the singular instance or existence of a specific thing being discussed, "a learning opportunity".

• 我希望能成為一個有用的人。

  I hope to become a useful person.

  The phrase "一個" specifies a singular identity or instance here, expressing the speaker's aspiration toward being useful.