Comparing "cengjing" and "yijing"

曾经 and 已经 both are adverbs that are used to indicate something happened in the past and sometimes can be used interchangeably. 曾经 is used in formal situations, whereas 已经 is used in informal and formal situations. The biggest difference between these two is 曾 is closer to “once” in English, expressing an action that took place in the past and has already finished up. On the other hand, 已经 is closer to “already”, expressing an action that took place in the past and has not necessarily finished up. A final difference, is that only 曾经 is used to express something that took place in the distance past (think “once upon a time, long ago…”).

B1HSK5ASV4567

	曾经 (céngjīng)	已经 (yǐjīng)
Meaning	already	once
Part of Speech	adverb	adverb
Formality	formal	flexible

:Yes

可参考：

都是副词，表示时间意义。

已经：表示动作、变化完成或者达到某种程度，时间是不久以前。

已经表示的情况有可能继续。

我已经是大学生了。

我已经吃完饭了。

曾经：表示所表示的动作或者情况已经结束，

曾经后的动词以“过”为主，也可以用“了”

我曾经去过杭州。

Sources and further reading

Websites

• 从语法表现看副词“已经”“曾经”的差异