sudden的副詞形式是什麼意思

What is the motivation behind this sudden change?

這種突然轉變背後的動機是什麼？

The sudden noise made her start.

突如其來的聲音嚇了她一跳。

His heart gave a sudden leap when he saw her.

他看見她時，心猛地一跳。

The children were surprised by the sudden entry of their teacher.

老師突然進來使孩子們感到意外。