例句：

　　The discussion focused on three main problems.

　　討論集中在三個主要問題上。

　　Suddently the lights focused on the piano on the stage.

　　燈光突然聚焦在舞臺上的鋼琴上。

　　We need to shift the focus of this debate.

　　我們需要轉換一下辯論的焦點。