接到通知要求补充材料，如下：
1. Submit evidence to establish how to benefit of the self-petitioner's work is of national importance. What effect would the proposed employment of the individual alien have on the United States as a whole?
2. Submit evidence to persuasively establish that national interest would be adversely affected if the beneficiary were required to obtain labor certification from the U.S. Department of Labor. Would a U.S. worker with the same minimum qualifications be able to perform the same occupation and serve the national interest to a similar degree? How will the individual alien serve the national interest to a substantially greater degree that other individuals having similar credentials in the field? Please submit persuasive documentary evidence to substantiate your response.
在已提供的材料中，已有10封推荐信，是不是还要追加推荐信？如果是，多少封为宜？
还要补充哪些材料呢？有点儿不知道从何下手。请大家帮帮忙，万分感谢！