Prepositions of time

at Christmas

on Christmas

in Christmas

at spring

in spring

on spring

on Mother's Day

at Father's Day

in Valentine's Day

at his birthday

in Sunday

at twelve o'clock

in night

in the afternoon

in Friday

on Sunday

on February

on five o'clock

at summer

at weekend

in night

at holiday

at Easter

at Thursday

at a quarter to five

at Valentine's Day

at Friday

in five p.m.

in summer

at their birthdays

on night

at Thursday

in August

in summer

on Saturday

at night