IN - ON - AT
For all English learners, from beginner to advanced, prepositions can always be a bit tricky. Some are much more strait forward than others. Above, before, during - all of these prepositions are relatively easy to use and do not require years to master. In, on, and at, however, these three prepositions can fool even the most confident non-native speakers. Used to indicate time and place, these prepositions do not come with standard rules, rather general guidelines that are not absolute.
In, on, and at are used to talk about time and place, from most general to most specific, in that order. For example, you would say;
"I live in Toronto, on Lytton Boulevard, at number 327."
You can see that when we're referring to a place, in is used for the most general and at is used for the most specific, and on is in the middle.
When we are referring to the location of objects, or other things (such as people), we must think about the physical meaning of each preposition.
"My clothes are in my wardrobe,"
"I left my cellphone on the table,"
"I am at the beach, let me call you back later."
In is used because the clothes are inside the wardrobe, on is used because the cellphone is on top of the table, and at is used because the beach is a specific location ("I'm at the train station").
In reference to time, the same guidelines apply in order of most to least specific. For example;
"I went to Australia in July,"
"My flight was on the 21 st ,"
"I arrived at 6:30 am in the morning."
July is a general point in time and that is why we use in to refer to the time, on is used to indicate a more specific time (the actual day of the flight), and at is used to say the exact time of arrival, the MOST specific point in time.
"In the spring I am going to travel to Rome," or, "In the spring I'm going to Rome."
"I can not come to your birthday because I have to work on Saturday, I'm sorry."
"Tonight, at exactly midnight there is going to be a shower."
"I woke up in the middle of the night last night because I had a nightmare."
"We saw two Lions on the weekend, and we also saw some elephants."
"There's going to be a thunderstorm at sunset, we should go back to the hotel."
"There are many beautiful beaches in Galicia."
"Can you please pass me my jacket on the hook."
"I left my ski-helmet at home, can I borrow yours for the day?"
"My brother went to many cities in south-east Asia. Vietnam was his favorite "
"It's important to pay attention to the seatbelt sign when you're on a plane."
"Do not worry about taking the subway, I'll pick you up at the airport. I'll be waiting for you. "
When native English speakers refer to their location by car, bus, train, and place, they use on. You might think that using in is correct, because when we use these modes of transportation we are not physically on them but rather in them however, it is more common to say,
"I am in my car, let me call you back," or,
"There are not many people on this bus."