好easy的英文

Future tense:
where will you be at eight o'clock?

Past tense:
where were you at eight o'clock?

p.s. 應該唔會用present tense, 因為用"where are you" 就係你而家係邊,
既然而家問, 就唔會加時間註明.

where will you be at eight o'clock?
你8時會在那裡?