What's the first stage of a negation according to the man?

根据那个人的说法，否定的第一阶段是什么？

youdao

Having completed the first stage, you can move on to step 2.

第一阶段完成后，你就可以接着进行第2步了。

《牛津词典》

The first stage in research is data collection.

研究工作的第一步是收集资料。

《牛津词典》

But the video effects used on stage are very much part of the twenty-first century.

VOA: special.2010.06.11

Two-and-one-half minutes after the Apollo Eleven launch, the first-stage rocket separated from the spacecraft.

VOA: special.2009.07.15

first stage engine on ascent. Proceed.Beautiful.Twenty-six .

VOA: special.2009.07.15

Its Russian liquid-fuelled first-stage is said to produce 1, 700 kilonewtons of thrust at launch.

BBC: South Korea halts rocket launch

So the signing of a "first-stage agreement" between Armenia and Azerbaijan does seem a distinct possibility.

BBC: Karabakh: Are Things Moving?

The Environment Agency (EA) said first-stage defences went up in Frankwell on Thursday evening.

BBC: Shrewsbury flood defences put up as river rises