"That's easy" 可以用英语表达为 "That's a piece of cake."。这个短语的来源可能源自英语俚语，最早的记录可以追溯到19世纪。
例句：
"Do you know how to solve this math problem?" "That's a piece of cake."
"I'm a pttle nervous about giving a speech in front of so many people." "Don't worry, it's a piece of cake."
中文翻译：
"你知道怎么解决这道数学题吗？" "那很简单。"
"我有点害怕在这么多人面前发言。" "别担心，那很简单。"