Whatever the features of regional English are, they are tiny compared with the mass of vocabulary and structure of "world standard" English, which is within easy reach of all.
Hi Taka, I agree that it is not at all clearly presented, but 'which' does refer to 'the mass (of vocabulary and structure)'-- by a process of logic, not grammar. It could refer equally to either 'mass' or 'WS English', grammatically. Furthermore, I am not enamoured of the semantics of 'the features.
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