In Chinese, sentences have a strict word order. However, when we speak about the season, year, date, time of day - we need to understand what kind of clause element they are. All time words can be an adverbial modifier of time, an attributive, or a complement of duration. Their position in the sentence will be changed depending on this.
The adverbial modifier of time answers the question “when?”. It can be stated either before or after the subject in a sentence.
We should distinguish it from the complement of duration, which answers the question “how long?”.
We will go to France in winter
dōngtiān wǒmen qù fǎguó
I get up at eight
wǒ bā diǎn qǐchuáng
When to use the preposition “in”
In colloquial speech, we don't need prepositions before the adverbial modifier of time.
To say “on Saturday”, in Chinese we just say “Saturday”.
To say “in 2020” in Chinese we just say “2020”.
However in formal speech and with the modal verbs 要 , 想 , 会 or 将 , we should put the preposition 在 or 于 before the time words.
adverbial modifier of time
He retired in 1970
tā zài yī jiǔ qī líng nián tuìxiū
The restaurant will be opened in November
cāntīng jiāng yú shíyī yuè chóngxīn kāizhāng
As an attributive “which?”
Time words can act as an attributive. In this case, they are stated before the object they define and they should be followed by the particle 的 .
when? which one?
We'll get on the night train
wǒmen huì shàng wǎnshàng de huǒchē
He invited me to watch movie at 8:00 p.m.
tā qǐng wǒ qù kàn bā diǎn de diànyǐng
As a complement of duration, “for how long?”
You can read more about the complement of duration here ↓