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...But Hornby was well aware that, of all the knowledge and skills which a language learner must master, the most important element, and the one involving the heaviest learning load, is an adquate working vocabulary. In this connection he saw clearly that, along with a good learner's grammar, a students of English can benefit enormously from a well-produced pedagogically-oriented monolingual dictionary. Such a work has the space to provide detailed practical information about the most important words of the language: pronunciations, key meanings, collocations, grammatical patterning, synonym comparisons, constraints on usage and so on. Hornby was that rare combination.

1. Can "combination" be used to describe a person, not a thing?

2. Does that mean Hornby was the one who rarely combinated them?

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anonymous1. Can "combination" be used to describe a person, not a thing?

Yes, in the given context.

anonymous2. Does that mean Hornby was the one who rarely combinated combined them?

No. It means it was rare for someone to know all those things, i.e., Hornby had a combination of all those skills.

CJ