Displays the first category without a parent id.

显示没有父id的第一个分类。

youdao

The EPC code itself belongs to the first category, since it indicates what was observed.

EPC 编码本身属于第一类，因为它指出观察的目标是什么。

youdao

This is the first category that involves strong social interaction between the children while they play.

这是儿童游戏中第一类需要大量社会性互动的游戏。

youdao

This is the first time there has been a separate category for Americana music.

VOA: standard.2010.01.24

And the first category identified is actually quite a sizeable one: the acquisition of private firms.

FORBES: Acquisitions -- finally something to cheer about...?

Into the first category, selfless behaviour that is not, fall acts that invite or assume reciprocity.

ECONOMIST: The benevolence of self-interest | The

Much of the knowledge, expertise and technology needed to understand business is channeled into the first category.

FORBES: Can the Business Media See the Forest for the Trees?