Abstract：This paper, adopting quantitative and qualitative study, investigates the influence of feedback upon the agreement amongst teacher-, self-, and peer-assessment, analyzes the data of students' thinking and summarizes the causes of assessing bias. Results show that feedback enhances students' ability of peer-assessing effectively. Peer-assessment is a beneficial supplement and highly related to teacher-assessment. However, self-assessing tends to overrate low performance and underrate high performance, which has weaker linear relationship with teacher-assessment.

Keyword：feedback;self-assessment;peer-assessment;oral English;formative assessment;