'At' just describes where something is located. It includes most of the other prepositions. The other prepositions are used either to be more exact or because they're more natural. If in doubt, it's usually safe to use 'at'. Note that 'at' treats location like a single point in space. If the location takes up a large amount of space (like a country), thean at may be inappropriate. 'In' describes when something is inside something else. In other words, it's used when something is inside an area (2D) or volume (3D). It's usually used with buildings and rooms, as well as places that have a border (such as cities, states and countries). 'On' is used when something is attached to the surface of something else. It can also imply that something is attached or sticking to something. It'll be clear when you read some examples. Examples: -If I'm on a building, I'm standing on the roof (or climbing the walls!). If I'm in a building, I've walked in the door and am in a room. -If I'm on a planet, I'm standing on the planet. If I'm in a planet, I'm deep underground! -A clock is on a wall. Termites live in the wall. -Grass grows on the ground. Ants live in the ground. -A show is on television (imagine it attached like a poster). Wires are in the TV. In all the examples above, 'at' can technically be used (although you could argue otherwise about the TV show). However, it isn't always natural. It's usually best to use 'at' when none of the other prepositions apply. I know this doesn't help, but you just need experience to know when 'at' is natural.

Where are you? I'm at the store. Where are you? I'm in the store. (I'm physically in the store). Both are correct. At = always location, always a specific time (at home, at the store, at the beach, at 4pm, at 3:30, at 1:10, etc) In = within something, within a period of time (In the box, in the refrigerator, in the car, in the room, in the beginning, in the past, in the afternoon, in the morning, in the evening, in the 1800s, in the 1900s, etc)

When it comes to time, prepositions are slightly different. 1) 'At + specific moment' - Describes exactly when something will happen. 2) 'In + time (indefinite noun)' - Something will happen between now and when that time finishes, or it happened in that amount of time. 3) 'In + time (definite or proper noun)' - Refers to something that happened or will in that time frame. This isn't used for days of the week. 4) 'On + day of the week' - Same as 3. Days of the week arw wierd. The numbers in the following examples correspond to the sentence type above. 1) At 8:00, I'll go to the beach. 2) In five minutes, I'll go to the beach. (If the time is now 8:00, you will leave at 8:05 or before) 2) In one year, he learned many languages. 2) In one year, he'll learn many languages. 3) In the five minutes, I'll go to the beach. ('The five minutes' has already been mentioned. This implies you'll be going to the beach in the five minutes it takes for something else to happen. The next example has context) 3) It'll take five minutes for the power to return. In that five minutes, I'll go to the store. 3) In November, I'll go to Japan. 3) He was born in 1994. 4) He was born on Thursday (ie. Thursday this week). 4) He was born on a Thursday (ie. any Thursday).

Well luz, they both are almost similar.... but here "at" describes that you are nearby the store or you are just standing outside the entrance.. but "in" is used while you are inside like when you are inside the store and shopping.... :) eg - i'm at the store near my place.....

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