Preposition: in, at, on (time)

AT

Exact Time:

 at 10 pm, at half-past 3, at quarter to five

Holiday periods:

 at New Year, at Christmas, at Valentine’s

Times:

 at night, at lunchtime, dinnertime, breakfast time

 at the weekend (British English) 

You can say:

I finish work at 5:00 in the afternoon.

The museums open at 8:00. 

I will meet her at Christmas. 

My father usually reads a newspaper at breakfast time. 

She plays football at the weekend. 

ON

Days:

on Monday, on Sunday, on Thursday, on Christmas Day

on the weekend (American English) 

Days + morning / afternoon / evening:

on Tuesday evening, on Wednesday afternoon 

Date:

on the 20th of January, on January 20th 

You can say: 

Bye, all! See you on Friday. Or See you Friday. (with or without on)

Do you go out on the weekend? 

I’m leaving on Friday evening. 

I was born on January 20, 1991. 

Let’s have a celebration on Christmas Day. 

IN

Years:

in 1991, in 2020, in 2010

Months:

in January, in February, in October

Seasons:

in the Summer, in the Autumn, in the Fall, in the Spring

Periods of the day:

in the morning, in the afternoon, in the evening

Decades:

in the nineties, in the sixties, in the 1980s

Centuries:

in the 18th century, in the 20th century

You can say: 

I’m taking a trip in September. 

I was born in 1991. 

There are a lot of people here in the Summer. 

She usually works out in the morning. 

Life was simple in the nineties. 

NO PREPOSITION

Next week, year, month, etc

Last night, Monday, year, etc

This evening, Sunday, month, etc

Every day, Thursday. Year, etc

Tomorrow

Today

Yesterday

You can say:  What are you doing this weekend?  We go on vacation every Winter. 

I’m meeting him next Monday. 

Why isn’t she at work today? 

What did you do yesterday?