只有 + Condition, 才 + Result
只有 (zhǐyǒu) means "only if" or "only when" and introduces a necessary condition for something to happen. It is typically paired with 才 in the result clause to emphasize that no other condition will suffice. This structure stresses exclusivity — the outcome depends entirely on the stated condition.
我只有一个妹妹。
Wǒ zhǐ yǒu yí gè mèimei.
I only have one younger sister.
只有他知道答案。
Zhǐ yǒu tā zhīdào dá'àn.
Only he knows the answer.
今天只有三个人来了。
Jīntiān zhǐ yǒu sān gè rén lái le.
Only three people came today.