以往的研究已经从学生、教师、课程和社会四种角度说明了学生课堂沉默的类型和沉默的原因，但从学生的视角出发，解读中国大学中二语习得课堂现状及原因的实证研究还较为匮乏。本研究通过课堂观察、半结构化访谈和在线问卷收集，揭示了85名大二英语专业的学生对自己在批判性阅读和写作课中沉默行为的看法以及造成学生课堂沉默的原因。结果表明:(1)学生的课堂沉默对学生实现学习目标既起消极阻碍作用，又起积极促进作用;(2) 学生积极沉默的原因包含个人学习目的和个人学习风格;(3)学生消极沉默的原因可以被分为四类:学生自身的原因、教师因素、课堂因素、社会因素。本研究的结果有助于全面深入地理解英语专业大二学生的课堂沉默行为，并有助于进一步提高二语习得的学习效果。

Previous research has already explained types and reasons for EFL learners' silence in classroom from students, teachers, courses and society perspectives, but empirical studies aimed at measuring the extent of micro-level silence within Chinese university L2 classrooms from students' perspective are notably lacking. This thesis responded to the gap in the literature by reporting on an intensive study which showcased how 85 sophomore English majors viewed their silence behavior in Critical Reading and Writing classes and why they kept silent through classroom observation, semi-structured interviews and online questionnaires. The results show that: (1) Students' silence can serve as both a negative obstacle and a positive facilitator in achieving their learning goals; (2) Students' personal learning goals and personal learning styles are two prominent reasons for their positive silence; (3) Students' reasons for keeping negative silent are classified into four categories: reasons of students themselves, reasons of teachers, the uniqueness of the lesson, and social factors. The findings of this study provide an overall and in-depth understanding of sophomore students' silence, which is conducive to improve SLA.