Both he and the author of the study believe that the way to mitigate the problem is to have states institute so-called graduated licensing systems, in which getting a license is a multistage process.

• 他和这项调研报告的作者都认为，缓解该问题的方法是让各州制定所谓的等级执照制。根据该制度，获得驾照是一个多级的过程。