Coincidence with "zhenghao"
正好 (zhènghǎo) can be used as an adjective or adverb to help express a coincidence, and it could be related to size, volume, quantity, degree, time, etc. This is similar to how we say in English “Oh, this shirt I grabbed was just the right size." or something like that.
Used as "happen to be"
You can also use 正好 to mean "happen to be."
Subj. + 正好 + [Verb Phrase]
- 我 正好 要 出去 ，垃圾 我 来 扔 吧 。I'm just about to leave. I'll take out the trash.
- 你 来 了 ！我 正好 要 找 你 。You are here! I was just looking for you.
- 他 正好 问 了 我 想 问 的 问题 。He happened to ask the question that I wanted to ask.
- 我 正好 也 在 这里 实习 。I happened to do my internship there too.
- 正好 你们 都 是 单身 。You both happen to be single.
- 我 明天 见 他 ，正好 可以 问问 他 这 件 事 。I'm going to meet with him tomorrow. I can just ask him about this matter.
- 我们 正好 也 要 去 那儿 ，一起 走 吧 。We just happen to be going there. Let's go together.
- 我 敲门 的 时候 ，他 正好 出门 。He just happened to be leaving the house while I was knocking at the door.
Used as "just right"
You can also use 正好 to mean "just right" or "just enough."
- 这 件 衣服 的 大小 正好 。The size of these clothes is just right.
- 水温 正好，不 冷 也 不 热 。The temperature of the water is perfect, not too cold, not too hot.
Sources and further reading