the first time相当于一个连词,后加从句,它也可以作名词
for the first time在句子中作状语
比如：I thought her honest ___ I met her.
A.first time
B.for the first time
C.the first time
D.by the first time
该题选C,意思是：第一次和她见面时,我就认为她诚实.
第一次”英语为the first time,the first time I met her相当于when I first met her.for the first time的意思是 “作为第一次”.
又比如:He cast his net for the first time.他撒了第一网.for the first time的作用相当于一个副词.
知道了吗?