为啥好久没更新？原因只一个：手冷。
好歹要备课，看到必修二第三单元的occasion, 今天就讲讲它了。
*occasion 时机，场合，时刻
a special/formal occasion
*on occasion =occasionally
偶尔，不经常地
Occasionally, we hang out in supermarkets after work .
偶尔我们下班后到超市闲逛。
*on this occasion / on that occasion
这一次，那一次
on one occasion
有一次
on several occasions
有几次
(1)On several occasions, I found him practising tai chi in the park.
有几次，我发现他在公园练习太极。
(2)I tend to get emotional on these occasions.
我在这些场合往往易激动。
(3)On one occasion, Jenny passed out in a PE class as a result of skipping breakfast.
有一次，Jenny 因为没吃早饭在上体育课时晕倒。
*occasion强调时间概念，作为先行词，后接定语从句时，用关系副词when连接，在从句中充当状语。
例句：
(1) I could think of very few occasions when my father spent Thinksgiving with us.
(2) Occasions are rare when my brother backed down even though he was in the wrong.
我哥哥即使错了，也很少认输。
(3) The photo is a constant reminder of that occasion when we visited the old people together in the nursing home.
这张照片使我不断想起我们一起去拜访敬老院老人的那一次。
*occasion后面接that /which 引导定语从句，在从句中充当主语或宾语。
(1)This is a special occasion that calls for a celebration.
这是个值得庆贺的特殊时刻。
(2)He recalled the occasion that turned him from an unknown singer into an overnight success.
他回忆起那一次，他从一个默默无闻的歌手一夜成名。
