只有一个的用法和样例：
例句
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只有一个男孩儿缺席，就是哈里。
Only one boy was absent, namely Harry. -
他只有一个心思--想的都是性事！
He's got a one-track mind -- all he ever thinks about is sex! -
这些票的有效期只有一个月。
These tickets are available for one month only. -
只有一个人能做这项工作，那就是你。
Only one person can do the job, namely you. -
只有一个卧室，所以我们得合著用。
There's only one bedroom, so we'll have to share.
