关于UTD的admission letter，有点不清楚，请教大家

一月底的时候，收到UTD的AD，是pdf格式的文件，当时没细看。最近仔细看了，有三段话不是很明白，想请教大家：

1. Please be aware that your major requires the following:
Once enrolled in the program:
-- You must make a B or higher in your first 12 hours of 6000 level courses
这是说入学后，6000的课程必须要达到B以上，否则就要被开除？

2. You must submit official documentation of your degree completion and final transcripts, and will receive an additional letter of information from the department of Electrical Engineering that may include additional conditions that must be met.
. 这是说，到学校报到时，要带上官方的学位证和成绩单。但后一句话时什么意思？系里还会发一封信，提出额外要求？两个月过去了，没收到这样的要求啊。

3. Please note that you will also receive an official admission letter in the mail for your records.
还会收到邮寄过来的正式的admission letter，但两个月过去了，也没收到。签证的时候自己打印pdf文件可以吗？还是一定要等到正式的letter？