Stringalphabet='ABCDEFGHIJKLMNOPQ'调用alphabet.substring(6,10)返回什么子字符串?
Stringalphabet='ABCDEFGHIJKLMNOPQ'调用alphabet.substring(6,10)返回什么子字符串?
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Stringalphabet='ABCDEFGHIJKLMNOPQ'调用alphabet.substring(6,10)返回什么子字符串?