是我的第一次。

It was my first time.

youdao

我第一次看到电视是我1956年到达美国的时候。

The first time I saw TV was when I arrived in the U.S. in 1956.

《柯林斯英汉双解大词典》

我第一次和他共事是在1971年，当时我们都处在职业生涯的起步阶段。

I first worked with him in 1971 when we were both on the lowest rung of our careers.

《柯林斯英汉双解大词典》

So now, the enzyme is locked up with being built, and the penicillin has effectively killed the bacteria.

所以这是我第一次感受到,我想在单个原子的层面上思考这些分子,所以这时我的专业转到了化学方向。

麻省理工公开课 - 化学原理课程节选

Actually, it's the first time I've seen him since the end of my senior which was about a year ago.

其实，自从大三之后我还是第一次见他，是一年前的事了。

我尊敬的教授 - SpeakingMax英语口语达人

I was going to say when you first start doing this, even people who have been doing it for a long time still go off on ten-minute daydreams before realizing that their minds were wondering.

我本想说第一次尝试时，但即便是修行多年的人,也会走神十分钟之久,方才意识到自己刚做了白日梦。

普林斯顿公开课 - 人性课程节选