Is used when no specific point of a place is being referred to.
Examples:
(a) ...at the hospital...
(b) ...at the school...
1. Is used to refer to an enclosed area.
(a) ...in the cafe...
(b) ...in the mall...
2. Is used for large territories such as continents, countries, states, etc. (For smaller areas, at is used)
(a) ...in Thailand...
(b) ...in Kampung Cahaya...
Both can be used for buildings. The difference is that 'at' refers to a building as an institution while 'in' refers to the building as a structure.
(a) Sarah works at a hospital.
(b) Sarah works in a hospital.
Is used to show that a particular place is located along a road, river, coastal line, etc.
(a) ...on Jalan Donggongan...
(b) ...on Sungai Kinabatangan...
at + a specific time on the clock
at + night
(a) We have a class at nine o'clock.
(b) We sleep at night.
in + periods longer/shorter than a day
(a) My birthday is in July.
(b) I was born in 1996.
on + a specific day of the week
on + a specific date
(a) I have badminton training on Sunday.
(b) I was born on August 16, 1995.
from (a specific time) to (a specific time)
(a) We have an extra class from 1.05 p.m. to 2.30 p.m.
(b) I have a piano lesson from 8.00 a.m. to 12.00 p.m.
Used when the first event mentioned happened first
(a) Siti took off her shoes before entering the house.
Used when the first event mentioned happened next
(a) We had lunch after the meeting.
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