A couple who have only one child are allowed to have a second baby in China.

在中国，只有一个孩子的夫妇可以生二胎。

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It is advocated in China that a couple only has one child.

在中国，提倡一对夫妇只生一个孩子。

《新英汉大辞典》

A lawyer couple can easily afford to put one child through Yale, but perhaps not four.

一对律师夫妇可以轻而易举地供一个孩子上耶鲁，但供四个恐怕很困难。

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The couple had one child, Napoleon Francis Joseph Charles.

FORBES: Connect

The couple had one child, a girl.

ECONOMIST: Jeanne Calment

One couple said their only child was taken away by mistake while they were working in another city.

BBC: Chinese babies 'confiscated for overseas adoption'