sud‧den‧ly S1 W1 / sʌdnli / 副词

quickly and unexpectedly :

I suddenly realized that there was someone following me.

George died very suddenly.

[句子副词]

Suddenly, the eagle opened its wings.

THESAURUS

suddenly used when something happens very quickly and unexpectedly : Suddenly, there was a loud bang. | I suddenly realized what had happened. | Her husband died suddenly at the age of 64.

all of a sudden suddenly – used especially in stories or descriptions of past events : All of a sudden, he takes a gun out of his pocket and shoots. | He just all of a sudden decided to leave.

without warning suddenly and with no signs that it was going to happen – used about bad or dangerous things : One day, he collapsed without warning. | Then, without warning, her husband left her.

out of the blue suddenly and unexpectedly – used especially when you hear from someone you have not seen for a long time or when someone tells you something that surprises you : She turned up on my doorstep, out of the blue. | The offer had come completely out of the blue.

at short notice British English , on short notice American English suddenly, so that there is not much time to prepare or change arrangements : He came into the side at short notice, when another player was injured. | Occasionally, tours may have to be cancelled at short notice.

on the spur of the moment used when talking about things you decide to do suddenly, without planning them beforehand : We all buy things on the spur of the moment. | On the spur of the moment, I decided to go and talk to her about it.