好问题，其实在整个美国本科考察applicants的众多参数中，interview这个环节也是很多的学生和家长会讨论的，但是面试的权重肯定没有美高的那么重了，不过也是很好地一个切入口来理解申请者，我们BE已经有很多讲座重点分享了美本面试的话题，可以去收听。基本上美国本科院校的面试都是以Alumni Interview为主的，所以对于给多少面试机会，其实需要参考的因素是很多的，比如你所在的区域的alumni的资源有多少等等，所以没法儿特别量化每年有多少学生会拿到面试的机会，关于面试的具体要求，普林斯顿大学是有明确的解释的：
Princeton offers optional alumni interviews. Interviews take place after the Admission Office has received your application. You may choose to opt out of the interview in the Princeton Supplement, and this choice will not put you at any disadvantage in the admission process. If you do not opt out, you may receive an email inviting you to interview with a member of our Princeton Alumni Schools Committee. If so, we encourage you to take advantage of this opportunity. The interviews are 30-45 minute informal conversations, where you can discuss the things that are important to you and also ask questions to someone who attended Princeton. We cannot guarantee that every applicant will receive an interview. This will depend on the availability of alumni in your area. Our dedicated alumni do manage to contact the vast majority of our applicants every year; however, if you do not receive an interview for any reason, it will not put you at a disadvantage since the interview is optional. We do not offer on-campus interviews. These interviews must not be recorded in any way, either by the interviewer or the applicant.
针对普林斯顿大学的官方解答，我们可以从以下几点来剖析：
1. 这个Alumni interview不是必须的，学校采用的是Optional，也提到了if you do not receive an interview for any reason, it will not put you at a disadvantage since the interview is optional.不参加也不会对于你的申请产生什么不利的影响，不过综合还是建议大家能抓住这个机会还是尽量抓住吧，上边也提到了学校在选拔学生的时候采用的是Holistic的选拔模式，还有我们BE之前的讲座也分享过普林斯顿大学面试官访谈的专题讲座，也强调了一条就是通过面试会让招办对你的了解更加全面一些，关于如何在面试中加分，就需要签约顾问给好好指导啦。
2. 整个面试的时长是30-45分钟，you can discuss the things that are important to you and also ask questions to someone who attended Princeton这个就是学校面试的主要原因，因为是双向的，一方面你可以通过这个面试分享你觉得对你来说重要的素材，此外还可以跟普林斯顿大学的校友提问，以便于你进一步了解学校
3. 是否能拿到面试的机会，其实并不能作为自己是否能被录取很重要的凭证，因为学校也提到了We cannot guarantee that every applicant will receive an interview. This will depend on the availability of alumni in your area. 学校不能保证每一个申请他们学校的学生都能拿到面试的机会，因为这个也跟他们学校的校友在你所在区域的数量有关系，所以就回到了上边提到的“每年大概有多少申请的学生可以拿到面试的机会，是否全部都能拿到面试的机会'这个问题了。
