最近几年来，国家正在大力整顿国家职业资格认证，所以想要获得国家职业资格认证的证书也是相当不容易的，那么如何在网上来查询国家职业资格证书?
In R, what is the most efficient way to count the length between 2 values. for example, i have vector x , which are all randomly choose from 1 to 100, how can i find out the length between the first\"
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