Sentence: If the 21st century is to be the Asia-Pacific century, they must be

[Gray]

"If the 21st century is to be the Asia-Pacific century, they must be."

Is this correct grammatically?
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First lesson - English, not english. I, not i. ~A student of English

[Mister Micawber]

No. Who is 'they' and what must they be?
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Native English teacher at Mister Micawber's

[Gray]

Sorry, it was my mistake. I missed the antecedent there which came in the preceding sentence.
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First lesson - English, not english. I, not i. ~A student of English