YOU SAID:
you should know that obamas last name is obama
INTO JAPANESE
あなたはオバマの姓がオバマであることを知っている必要があります
BACK INTO ENGLISH
You need to know that Obama's surname is Obama
INTO JAPANESE
あなたはオバマの姓がオバマであることを知る必要があります
BACK INTO ENGLISH
You need to know that Obama's surname is Obama
That didn't even make that much sense in English.