occasion/ ə'keɪʒən /

1.noun [c] 
(moment) 时刻

2.noun
(event,celebration) 场合

3.noun
an occasion for sth/for doing sth (opportunity) 某事/做某事的机会

4.vt.[frm] 
(cause) 引起

on occasion(s)
有时
to rise to the occasion
应付自如
a sense of occasion
隆重感