I often say "supporting letter" and clarify that it's for green card application only, which sounds clearer in its purpose. When I ask for such a letter, I'd express my need and appreciation for their help, but also give them a chance to say no, if they are not comfortable with it.
Editas今天下午有个seminar在Broad,感兴趣的同学可以去看看。 An Afternoon with Katrine Bosley CEO of Editas Medicine Wednesday, February 10th 4:00 - 5:00 pm Broad Institute First Floor Auditorium Katrine Bosley will be speaking with the MIT Biotech Group community! Katrine is the CEO of Editas Medicine, which is a transformative gene editing company founded by world leaders in the fields of genome editing, protein engineering, and molecular and structural biology, with specific expertise in CRISPR/Cas9 and TALEN technologies. Prior to Editas, Katrine had served in a variety of successful biotechnology companies across her 20- year career in the industry. Most recently, she served as the Entrepreneur- in-Residence at the Broad Institute and as a review committee member for the Translation Fund at the Wellcome Trust. Prior to that, she had served as the CEO of Avila Therapeutics, which was acquired by Celgene, and had also served as the VP of Business Development and VP of Strategic Operations at Adnexus Therapeutics.