像USC website上面所说的,“It is preferred (though not required) that one of these letters be from an academic source (e.g. professors) that can attest to your ability to successfully complete a rigorous graduate degree program. The other letter may be from a non-academic source (e.g. employer) that is familiar with your work history and/or career goals.”这是否意味着最好还是找个教授来写推荐信呢?