To say “again”: zài 再 vs. yòu 又 When you say - Cchatty

To say “again”: zài 再 vs. yòu 又

When you say that someone will do something again in the future, use zài 再:

I will go to China again next year.
Wǒ míngnián huì zài dào Zhōngguó qù.
我明年会再到中国去。

We’re going to see that movie again tomorrow evening.
Wǒmen míngtiān wǎnshang huì zài kàn nèige diànyǐng.
我们明天晚上会再看那个电影。

When you say something happened again in the past, use yòu 又:

I went to China again last year.
Wǒ qùnián yòu dào Zhōngguó qù le.
我去年又到中国去了。

We saw that movie again last night.
Wǒmen zuótiān wǎnshang yòu kàn le nèige diànyǐng.
我们昨天晚上又看了那个电影。

HOWEVER, be aware that before certain helping verbs, such as shì 是 (am, is, are), xiǎng 想 (think), néng 能 (can/able to), yào 要 (want), yǐhòu 以后 (after), and huì 会 (can/know), you can only use yòu 又 (again, regardless of tense):

Tomorrow there’s going to be a test again.
Míngtiān yòu shì yíge kǎoshì.
明天又是一个考试。

They need to/want to see the doctor yet again this afternoon.
Tāmen jīntiān xiàwǔ yòu yào qù kàn dàifu.
他们今天下午又要去看大夫。