问题补充：
I toured Jiu Zhai Gou, I was deeply impressed with its beautiful scenery.
A. For the first time
B. At first
C. It was the first time
D. The first time
答案：
A. For the first time
B. At first
C. It was the first time
(答案→)D. The first time
解析：名词性短语充当连词。本题中的the first time是一个名词性短语，在句中充当连词，连接起一个时间状语从句。句意：第一次我去九寨沟旅游的时候，我被它的美景深深地打动了。故D正确。AB项是介词短语，都是单独在句中做状语。D项是个固定句式，和句子的意思不相符。名词性短语充当连词在高中英语中有很多，如the moment一…就…；等。
