T is the ten digits of a two-digit positive integer

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T is the ten digits of a two-digit positive integer
GRE的mathematics conventions有个例子是“T is the tens digits of a two–digit positive integer,so T is an integer from 1 to 9”,我不太明白前半句话的意思,a two–digit positive integer 应该是一个两位的正整数,前面的the tens

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