I.

1.student-centred

2.teaching process; teaching objectives

3.reasonable

4.Effective

5.realistic

II.

1.Key: The two principles are interrelated: on the one hand, to conduct the effective principle, teachings activities must be student centered and must obey the student-centered principle; on the other hand, teaching activities based on the student-centered principle are certainly effective in practice. They interact with each other and reciprocate each other.

2.Key: Student-centered activities are most effective. These activities are conducive to students’ needs, consistent with the reasonable teaching plan, use language that is easy to understand, pay attention to students’ response and encourage students to ask questions and evaluate themselves.