I told her my secret in the mistaken belief that I could trust her.

我误以为可以相信她，就把我的秘密告诉了她。

《牛津词典》

Paradoxically, the parents of such children encourage this demanding behavior in the mistaken belief that by giving their children everything they can their children will be happy.

矛盾的是，正是这些孩子的父母促成了这种苛求的行为，他们错误地认为，只要给了孩子他们所能给予的一切，孩子就会快乐。

youdao

I helped him in the mistaken belief that he needed me.

我误以为他需要我所以去帮助他了。

youdao

Also, would a traveler have legal recourse for damages if agents seized a proper debit card in the mistaken belief that it was a reportable prepaid card?

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The Great Inflation of the 1970s was caused by repeated bouts of excessive money printing by the Federal Reserve and other central banks in the mistaken belief that government could eradicate the normal ups and downs of economic activity.

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Several audit firm professionals tried to convince the SEC and PCAOB staff that they were mistaken in the belief that broker-dealer auditors could not sign the broker-dealer audit opinion as well as help implement accounting software, prepare period-end journal entries and compile those same financial statements and regulatory reports that they would audit.

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