someone is no foolsomeone is not easily deceived:The teacher won't believe your little brother took your homework – he’s no foolhttps://dictionary. cambridge. org/احمق نبودن، به راحتی گول نخوردن 
 ...  [مشاهده متن کامل]  
be no fool
 ( also be nobody's fool
Be a shrewd or prudent person. 
‘Alex was very clever at school and was nobody's fool. 
زیرک و عاقل و باعقل بودن، احمق نبودن
no/nobody’s fool
intelligent and with a lot of experience of life so that you do not allow other people to trick you
Her eyes shone with intelligence: she was nobody’s fool. 
باهوش بودن، با تجربه بودن جوری که کسی نتونه گولتون بزنه
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