These three common prepositions are used before nouns or pronouns to indicate time or location.

Time

Use in with

Months: in April

Years: in 2011

Seasons: in the winter

Certain parts of the day: in the morning, in the afternoon

Use on with

Days of the week: on Tuesday

Dates: on June 20, 2011

Use at with

Specific times: at 8 p.m., at noon

Other parts of the day: at night, at dawn, at dusk

Location

Use in with

Geographic places: in San Francisco, in rural areas

Enclosed areas: in the stadium

Use on with

A surface: on a shelf

Forms of public transportation: on the bus

Street names: on Main Street

Floors of buildings: on the fourth floor

Some areas of the country: on the Gulf Coast

Use at with

Specific addresses (number and street): at 130 Washington Street

Named locations: at Juanita’s house

General locations: at the college

Locations with specific functions: at the library

For more on prepositions, see 1g.