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 "just right"
When used with a noun, use 正好 right after it.
Subj. + 正好
- 这 件 衣服 的 大小 正好 。The size of these clothes is just right.
- 两 个 人 正好 ，一 个 说，一 个 演 。Two people is perfect. One to speak and one to act.
- 水温 正好，不 冷 也 不 热 。The temperature of the water is perfect, not too cold, not too hot.
- 这 个 楼层 正好，不 高 也 不 低 。The floor is perfect, not too high, not too low.
- 两 个 房间 正好 ，我 一 间 ，我 爸 妈 一 间 。Two rooms are perfect. One for me and one for my parents.
You can also use 正好 along with 得 to mean "just right", as shown in the following examples.
Verb + 得 + 正好
- 你 来 得 正好，不 早 也 不 晚 。You arrived at just the right time, not too early and not too late.
- 米饭 煮 得 正好，不 硬 也 不 软 。The rice was made perfectly, not too hard and not too soft.
- 盐 放 得 正好，不 咸 也 不 淡 。The amount of salt you put was just right, not too salty and not too bland.
- 钱 给 得 正好，不 多 也 不 少 。The money you gave was just right, not too much and not too little.
- 菜 点 得 正好，都 吃完 了 。The food you ordered was perfect. We finished them all.
Used as "about to do"
正好 + [Verb Phrases]
- 我 正好 要 出去，你 要 我 帮 你 带 什么 东西 吗 ？I'm just about to leave. What do you want me to bring for you?
- 我 现在 正好 没 事 做，可以 帮你 照顾 一下 宝宝 。I just happened to have nothing to do now so I can help you with the baby.
- 你 来 了！我 正好 要 找 你 。You are here! I've been looking for you.
- 他 正好 是 学 这 个 专业 的，也许 可以 帮 你 。His major is just this. Maybe he could help you.
- 你们 都 要 来 ？太 好 了 ！正好 帮 我 搬 家 。Are you all coming? Great! So you can help me to move.
Sources and further reading