1, She is the most beautiful girl whose I have ever met
-that
2, She can't speak English,whom is a disadvantage
-which
3, The policeman must try to catch those people whom drive dangerously
-who
4, The person about who I told you yesterday is coming here tomorrow
-∅
5, Mother's Day is the day where children show their love to their mother
-when
6, Do you know the reason when we should learn English?
-why
7, The woman who she told me the news was not a native citizen here
-∅
8, New Year Day is the day where my family members gather and enjoy it together
-when