32. break out (火灾、战争等)爆发

World War II broke out in 1939. 第二次世界大战是1939年爆发的。

33. come about 发生

(是不及物动词短语，无被动语态)How did it come about that you got lost? 你怎么会迷路了呢?

34. watch out (for…) 当心，提防

You’ll be cheated if you don’t watch out. 如果你不当心，就会上当受骗。

Watch out for cars when you cross the road. 过马路时要当心车辆。

35. 倍数的表达方法：

1)A is + 倍数 + as + adj./ adv. + as B

“A 是B的……倍”

2)A is + 倍数 + 比较级 + than B

“A比B……倍”

3)A is + 倍数 + the size (height, length, width等) + of B

“A 是B的……倍”

The population of China is about six times as large as that of the United States. 中国的人口大约是美国的6倍。

The jet fighter flies three times as fast as sound. 这架喷气式战斗机的飞行速度是音速的3倍。

This room is three times larger than that one. 这个房间比那个房间大3倍。

This room is three times the size of that one. 这个房间是那个房间的3倍大。

以上就是精品学习网的编辑为您准备的2014年高中英语知识点总结：第四单元知识点