它主要存在于贫困家庭的孩子中。

It exists mostly among children from poor families.

youdao

饱和脂肪主要存在于肉类和乳制品中，不过一些坚果和植物油中也含有这些脂肪。

Saturated fats are fats that are found principally in meat and dairy products, although some nuts and vegetable oils also contain them.

youdao

矛盾的是，虽然液态水所需的温度只存在于太阳系内部，但生命的关键组成部分，包括水本身，却主要存在于小行星带之外。

Paradoxically, while the temperatures required for liquid water exist only in the inner solar system, the key building blocks of life, including water itself, occur primarily beyond the asteroid belt.

youdao

The opposition is between poetry that makes money and poetry that, precisely because it is good poetry as modern poetry defines it, does not.

对立性主要存在于为了赚钱的诗歌和,不为金钱的角度，现代诗歌意义上的,好诗歌之间的分歧。

耶鲁公开课 - 现代诗歌课程节选

Well, up until probably ten years ago, this was the primary propellant in just about every kind of spray thing that we had, hairspray, everything.

好吧，直到大概十年前，作为主要推进剂,存在于我们的每一个喷射器里，发胶，以及一切。

麻省理工公开课 - 固态化学导论课程节选

It can separate between what's part of yourself and what's foreign, and it does that by presenting, by recognizing antigens that are presented in the context of the major histocompatibility complex, MHC.

免疫系统可以识别出哪些是属于你的,哪些是外来的,它通过呈递和识别抗原达到目的,而抗原是存在于,主要组织相容性复合体中的

耶鲁公开课 - 生物医学工程探索课程节选