硕士研究生的英文表达有以下几种：
master's degree student
postgraduate student for a master's degree
Master degree candidate
graduate student for a Master's degree
建议根据具体的语境选择合适的表达方式。例如，在正式文件或学术场合中，“master's degree student”和“postgraduate student for a master's degree”更为常见和恰当。在日常交流中，“graduate student for a Master's degree”和“postgraduate”则更为简洁和常用。