根据句意, 首字母及汉语提示填写所缺单词。(5’)

小题1:Smoking is a bad ___________(习惯).

小题2:You can write a poem about________(大自然).

小题3:He had been operating on a wounded__________(战士) when he accidentally cut his hand.

小题4: Helen Keller, the well—known writer and __________(教育家) died at the age of 88.

小题5:The book is ___________（值得…的）reading again.

混响器是利用电子线路的延迟和反馈产生多次( )效果后，模拟混响效果的。

A．反射声

B．回声

C．绕射声