她给了他一个快乐、坚定、看似不自然的微笑。

She gave him a bright, determined smile which seemed unnatural.

《柯林斯英汉双解大词典》

她面带不自然的微笑向我表示欢迎。

She welcomed me with an artificial smile.

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亲友们来探望他，带着不自然的微笑，反复说他气色很好。

Friends and relatives paid him visits and, with exaggerated smiles, assured him that they thought he looked fine.

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