He lost both of his parents in the big earthquake, but       for him, a kind couple adopted him and took good care of him.

A．suddenly

B．naturally

C．obviously

D．luckily

适用于开展以教师讲授和课堂演示为主的教学环境是（）

A.多媒体教室环境

B.图书馆学习环境

C.多媒体网络教室环境

D.专业实验室环境