I toured Zhangjiajie, 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
网友回答
A. For the first time
B. At first
C. It was the first time
(答案→)D. The first time
解析：逗号前后都是一个句子，所以整个句子缺少连词，只有The first time是连词，引导的是时间状语从句，故选D。