At the same time, I am a little sad because I have to say goodbye to my classmates and teachers.

同时，我也有点难过，因为我要和我的同学和老师说再见了。

youdao

I work not because I have to, but because I want to.

我不是必须工作，而是我想工作。

youdao

When I get home, I can't watch TV because I have to practice the piano.

我回家不能看电视，因为我要练习钢琴。

youdao

You've hit on the very idea. I wanted to spend the money on one thing, because I have to turn in a report for it, and I hate itemizing."

VOA: special.2011.08.13

I am only counting in one direction, 2 so I have to multiply this whole thing by two because I have to count both directions.

因为我只是在一个方向上计数，所以我要把这些所有乘以,因为我们必须考虑到2个方向。

麻省理工公开课 - 固态化学导论课程节选

because I have to walk a really long way from the subway to get to the Yoga studio.

因为我从地铁到瑜伽工作室要走很长的一段路。

上东区的氛围 - SpeakingMax英语口语达人

So I'm going to go, because I have to go look at the tent.

WHITEHOUSE: First Lady Michelle Obama Previews the U.K. State Dinner

"I stay here because I have to get healthy before I travel, " he said.

BBC: Rafael Nadal loses to Nikolay Davydenko at Qatar Open

Because I have to tell you I'm feeling pretty fired up and ready to go.

WHITEHOUSE: Remarks by the First Lady at a Campaign Event