就是
jiù shì
Emphasis with "jiushi"
就是 is the stubborn "simply" — it insists, often against opposition.
Subj. + 就是 + Verb Phrase
How it works
我父母就是不让我一个人去 — my parents simply won't let me go alone. The 就是 signals that the speaker finds it unreasonable and unmovable.
It also identifies exactly: 这就是我要的 — this is precisely what I wanted.
As a one-word reply, 就是! means "exactly, that's what I'm saying".
Examples
wǒ fù mǔ jiù shì bú ràng wǒ yí gè rén qù
我父母就是不让我一个人去。
My parents simply won't let me go on my own.
zhè jiù shì wǒ yào de
这就是我要的。
This is exactly what I wanted.
tā jiù shì bù tīng
他就是不听。
He just won't listen.