the first time/at the first time/ for the first time

the first time 第一次，是名词，在句子中只能做名词的成分。
at the first time 是介词短语，是“在第一次”
for the first time 也是第一次，是个副词短语，在句子中做状语。
例子：
He won the match at the first time.
他在第一次比赛中就获胜了。
We should inform the insurance agent at the first time.
我们应在第一时间通知保险公司代理。
For the first time I felt repentance and sorrow.
我第一次感到后悔，感到难过。

the first time 第一次，连词the first time i saw him i fell in love with him
at the first time 是介词短语，是“在第一次”
for the first time 也是第一次，是个副词短语，在句子中做状语。

the first time 第一次,是名词,在句子中只能做名词的成分.
at the first time 是介词短语,是“在第一次”
for the first time 也是第一次,是个副词短语,在句子中做状语.
例子：
I felt nervous the first time I gave a speech to many students.
我第一次给学生做演讲时感到很紧张.
He won the match at the first time.
他在第一次比赛中就获胜了.
I felt repentance and sorrow for the first time .
我第一次感到后悔,感到难过.

the first time +状语从句
如： The first time I went to England, I was impressed by its beauty.
=When I went to England for the first time,. I was impressed by its beauty.
at the first time 和for the first time 都是介词短语，作句子的时间状语的
the first time 是引导状语从句的连接词