Mandarin Chinese has a grammatical function for emphasizing parts of a sentence. Emphasis can be placed on:

    place
    purpose
    method
    time

The part of the sentence that is to be stressed is preceded with shì (是), with de (的) being placed at the end of the sentence.
Notes on Shi … De

    This construction is only used for events in the past.
    Shì can be omitted in positive sentences, but never in negative sentences.
    This construction is used to clarify a situation or to provide an explanation.

Examples of Shi … De

Emphasized words are in italics.

    Wǒ (shì) lái Táiběi zhǎo péngyou de.
    I came to Taipei to visit a friend.
    我(是)來台北找朋友的｡

    Wǒ zài dàxué shì xué yīnyuè de.
    I studied music at university.
    (trad) 我在大學是學音樂的。
    (simp) 我在大学是学音乐的。

    Tā (shì) sān yuè qī hào dào Shànghǎi qù de.
    He went to Shanghai on March 7th.
    (trad) 他(是)三月七號到上海去的｡
    (simp) 他(是)三月七号到上海去的｡

    Tā dào Shànghǎi shì qù zuò shēngyi de.
    He went to Shanghai for business.
    他到上海(是)去做生意的｡

    Lín xiǎojie bú shì cóng Běijīng huílai de.
    Miss Lin did not come back from Beijing.
    (trad) 林小姐不是從北京回來的｡
    (simp) 林小姐不是从北京回来的｡