The adult Galapagos tortoise clearly is too big for a trip hundreds of kilometers across the ocean.

VOA: special.2009.12.16

Because the pond is deep enough for an adult to wade into but too deep for a child to stand.

这个池塘不深，一个成年人足以趟过,然而小孩子却无法站立。

普林斯顿公开课 - 人性课程节选

So this, too, fairly straightforward and yet and this was a socially awkward moment I had to ask her are you an adult or a senior?

这个也相当简单,这是一个社会尴尬的时候,我必须问她是一张成人票还是老人票？

哈佛公开课 - 计算机科学课程节选