How did Hong Haier recognize Niu Wangmo as the Monkey King?

First of all, the Monkey King said that Tang Priest was released, and Hong Haier became suspicious. Then Hong Haier asked the Monkey King why I didn't bring a present for my birthday. The Monkey King said he was in no hurry to bring it, and he would send it another day, so he got it.

Hong Haier asked Xiaoyao when he saw Niu Wangmo. Xiaoyao said he met him halfway. At this moment, Hong Haier is still not sure whether this NiuWangMo is true or not.

Later the Monkey King said the word "seventy-two changes". Can't his father change 72? In order to further confirm the authenticity of Niu, Hong Haier asked about his date of birth, because Niu always talked about Hong Haier's birthday on weekdays, and the Monkey King was betrayed.

Extended data:

Hon Hai 'er heard that eating the Tang Priest's flesh can make him live forever, so he pretended to be a suffering child, hung his hands and feet on a tree with hemp rope, and led Tang Priest and his disciples to rescue him. But the Monkey King saw it through, and directly swept the Tang Priest away with strong winds, and then fought with the Monkey King, turning him into a Guanyin-like liar to catch Pig Bajie.

The Monkey King couldn't subdue the Samadhi fire for a while, and it was hard to put it out even if it fell on the Dragon King of the Four Seas. The Monkey King had to invite Guanyin Bodhisattva to surrender Hong Haier, put out Samadhi fire with nectar from a jade bottle, and sent his apprentice Mu Cha (Mu Bing) to borrow thirty-six plowshares from his father, King Tota, and hide under the throne of the lotus platform to trap Hong Haier.

Guanyin Bodhisattva put five gold hoops (one of the three gold hoops) on Hon Hai, and finally subdued Hon Hai. He followed Guanyin Bodhisattva, became an auspicious boy, and finally became a positive result.