sudden的名词形式为suddenness。sudden作为形容词，含义为“突然的”、“忽然的”、“骤然的”、“出乎意料地”；而suddenness作为sudden的名词形式，中文含义为“意外”、“突然”。
一、sudden的基本意思及用法介绍
sudden作为形容词，意为突然的;忽然的;骤然的。
例句：Don't make any sudden movements.
不要突然地做任何动作。
It was only decided yesterday. It's all been very sudden.
这是昨天才决定的，一切都非常突然。
He had been deeply affected by the sudden death of his father-in-law...
岳父的猝死使他十分伤心。
What is the motivation behind this sudden change?
这种突然转变背后的动机是什么？
His heart gave a sudden leap when he saw her.
他看见她时，心猛地一跳。
He had a sudden impulse to stand up and sing.
他突然心血来潮，想站起来歌唱。
She was totally bewildered by his sudden change of mood.
他的情绪突变搞得她全然不知所措。
His sudden entrance took everyone by surprise.
他的突然出场使所有人都感到意外。
二、suddenness的基本含义及双语例句
suddenness作为名词，意为意外、突然。
例句：All of a sudden she didn't look sleepy any more.
她突然看起来一点都不困了。
The president's final decision came with stunning suddenness.
总统之最后决定的突然性令人吃惊。
The Soviet decision came with stunning suddenness.
苏联方面的决定来得十分突然。
America's allies were rather taken aback by the suddenness of this announcement.
这份突如其来的声明使美国的盟友们大吃一惊。
Once more, the two spectators started, as he turned upon her with a frightful suddenness.
两个旁观者又吓了一跳，因为他令人害怕地突然转向了她。
I know the suddenness of it must have been a dreadful shock; and I just can't tell you how sorry I am.
这一突然不幸对你一定是一沉重打击。我无法表达我的悲痛之情。
