Meaning of zēng:
曾
surname Zeng; great- (grandfather, grandchild etc)
Wǒ yǒu yīgè péngyǒu xìng Zēng.
我有一个朋友姓曾。
I have a friend with the surname Zeng.
Tā shì wǒ de zēng zǔfù.
他是我的曾祖父。
He is my great-grandfather.
once; already; ever (in the past); previously
Wǒ céng jīng qùguò nàlǐ.
我曾经去过那里。
I have once been there.
Wǒ céng qùguò nàgè dìfāng.
我曾去过那个地方。
I have already been to that place.
Tā céng zài Běijīng shēnghuó.
他曾在北京生活。
He once lived in Beijing.
Wǒ céng zài Běijīng gōngzuò.
我曾在北京工作。
I previously worked in Beijing.
former
Tā céng zài zhèlǐ gōngzuò.
他曾在这里工作。
He used to work here.
(past tense marker used before verb or clause)
Tā céngjīng shì yī gè chūsè de yùndòngyuán.
他曾经是一个出色的运动员。
He was once an outstanding athlete.