Doubts about the correct spelling/choice of words

0 Hello everybody,02br
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00I'm writing a small essay for a school assignment and was having it corrected by a good friend. This has led to an enormous discussion about how to write the following 2 sentences:02br
00My questions are probably very simple but keep in mind I'm not a native english speaker 05002br
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01u00Sentence 1:02u02br
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00This was the sentence which kept lingering in my parents’ heads after their visit to the 01a01span00gynaecologist02span02a02br
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00Or02br
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00This was the sentence which kept lingering in 00my parents's heads01b00 02b00after their visit to the 01a01span00gynaecologist02span02a02br
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00Or (head instead of head01b00s)02b02br
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00This was the sentence which kept lingering in my parents’ head after their visit to the 01a01span00gynaecologist02span02a02br
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01u00Sentence 2:02br
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02u00Now01span00,02span00 my parents would discover how having twins can change someone's life.02br
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00Or 02br
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00Now01span00,02span00 my parents would discover how having twins could change someone's life.02br
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00Many many thanks!02br
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00Vicky02br
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01span02span00 010id5