Final answer:
The group of words 'Gongs, circular metal percussion instruments' acts as a noun phrase because it lacks both a subject performing the action and a verb. Therefore, it is a phrase, not a clause, which generally contains both a subject and a verb and forms a complete thought.
Step-by-step explanation:
In English grammar, identifying whether a group of words is a phrase or a clause is essential for proper sentence structure. A clause is defined as a group of words that contains both a subject and a verb and may be independent or dependent.
In contrast, a phrase is a group of words that acts as a single unit within a sentence but lacks a subject or verb. Consequently, the group of words 'Gongs, circular metal percussion instruments,' does not contain a verb or a subject that performs an action. This group of words therefore functions as a noun phrase introducing the subject 'gongs' for the rest of the sentence, making it not a clause but a phrase.
Clauses are pivotal in sentence construction, providing the necessary structure by containing both a subject and a verb. For example, the clause 'where they were and sometimes still are-used in ceremonial events' from the sentence given has both a subject ('they') and a verb ('are-used'), which qualifies it as a clause. This clause provides additional information about the history and use of gongs in China.