IsawBobplaythepianoatJohn'spartyandonthathewassimplybrilliant.为什么选circumstance而不是occasion?

Question

I saw Bob play the piano at John's party and on that ___ he was simply brilliant.为什么选circumstance而不是occasion?

Answer 1

和circumstance搭配的只有in或under
in the circustances/ under the circumstances 而且中文意思是在那种情况下,与此句话不符.
on great occasion译为在大庆时期,可以变通为on that occasion.因此,此句话应该是,我在John举办的晚会上,看到Bob弹钢琴了,那时的他真是光彩夺目.
综上,认为答案错了.