1.unsure (adj.)不确定的；缺乏信心的，无把握的；不稳定的
We were all unsure about when she left Taipei.
我们都不太清楚她什么时候离开台北。

2.watch (v.)观看；监视；看守；注意
Yesterday I was watching a movie.
我昨天在看电影。

3.happened (v.)出现；碰巧；发生（happen的过去式和过去分词）
This is probably something that never happened.
这应该是从未发生过的事情。

4.thing (n.)事件；形势；东西；事物；家伙；事业
I don't want this to become a thing between us.
我不想让这成为一件不愉快的事情。