幼儿语言教育的活动观
参考答案：
是指以活动的形式来组织幼儿语言教育过程，帮助幼儿学习语言。
At the beginning of class, the raise of desks could be heard outside the classroom. [ ]
A. opened and closed
B. to be opened and closed
C. being opened and closed
D. to open and close
什么是AIS？简述其发展历程。
