YOU SAID:
Did you know it is Halloween?
INTO JAPANESE
ハロウィンって知ってましたか?
BACK INTO ENGLISH
Did you know about Halloween?
INTO JAPANESE
ハロウィンについてご存知ですか?
BACK INTO ENGLISH
Do you know about Halloween?
INTO JAPANESE
ハロウィンについて知っていますか?
BACK INTO ENGLISH
Do you know about Halloween?
That didn't even make that much sense in English.