Enskubók

Prepositions of Time — In, On and At

The prepositions in, on and at are commonly used to say when something happens. Although they all refer to time, they are used with different kinds of time expressions. The main difference is how specific the time reference is. We normally use in for longer periods, on for particular days and dates, and at for exact times or specific moments.

Let’s begin with in. We use in with months, years, seasons and centuries. For example, My birthday is in September, She was born in 1995, We usually go skiing in winter, and The castle was built in the fifteenth century. We also use in with parts of the day: I drink coffee in the morning, He usually studies in the afternoon, and They watch television in the evening.

The preposition on is used with days of the week and specific dates. For example, I have an English lesson on Tuesday, We’re meeting our friends on Saturday, and The museum opened on the tenth of June. We also use on when we mention a particular day together with a part of that day. Compare I usually work in the morning with I have a meeting on Monday morning. The first describes a general period of the day, while the second refers to a particular morning.

Finally, we use at for precise times and particular moments. For example, The train leaves at seven o’clock, We usually have lunch at half past one, and The film starts at eight fifteen. Other common expressions include at noon, at midnight, at lunchtime and at night. Notice that we say in the morning, in the afternoon and in the evening, but at night.

There are also some expressions that do not need a preposition. We say I saw her yesterday, We’re leaving tomorrow, He arrived last Friday, and I’m going to call you next week. We do not add in, on or at before these expressions.

A useful way to remember the difference is to imagine moving from a longer period to a more precise moment. Someone might say, I was born in June, on a Friday, at six o’clock in the morning. The month takes in, the day takes on, and the exact time takes at. Once you become familiar with these patterns, choosing the right preposition becomes much more natural.

For and Since — Duration and Starting Points

The words for and since are both used to talk about time, but they express two different ideas. For tells us how long an action or situation lasts, while since tells us when it began. This distinction is especially important when talking about situations that started in the past and continue into the present.

Let’s begin with for. We use it with a period of time, such as ten minutes, two hours, three days, six months or five years. For example, I waited for twenty minutes, They lived in London for three years, or We’ve been friends for a long time. In each sentence, for answers the question “How long?” The expression tells us the duration, but it does not tell us exactly when the situation started.

Since, on the other hand, identifies a starting point. We use it with a particular time, date or event, such as Monday, yesterday, last summer, 2020 or the day we met. For example, She’s been here since Monday, I’ve known him since 2018, or We haven’t seen each other since Christmas. We can also use since with a complete clause: I’ve lived in this town since I was a child, or She has worked from home since she changed jobs.

Compare these two sentences: I’ve worked here for five years and I’ve worked here since 2021. Both describe a situation that began in the past and continues now. The first tells us the length of time, while the second identifies the year when it started. Another example is We’ve been waiting for an hour compared with We’ve been waiting since nine o’clock. The situation is the same, but the time information is different.

There is also an important connection with verb tenses. For can describe both completed and continuing situations: I stayed in Paris for a week describes a finished visit, while I’ve lived in Paris for ten years suggests that I still live there. Since is especially common with the Present Perfect because it connects a starting point in the past with a situation that continues into the present.

A useful way to remember the difference is to ask two simple questions. If you want to know how long, use for: for two hours, for three weeks, for many years. If you want to know since when, use since: since Monday, since 2015, since I started school. Remember: for describes duration; since identifies the starting point.

Besides in, on, at, for and since, English uses several other prepositions to describe when things happen, how events are connected in time, and when activities begin or end. Some of the most useful are before, after, during, until and by. Although they all refer to time, each one expresses a different relationship between events.

Let’s begin with before and after. These two words help us describe the order of events. Before means that something happens earlier than another event, while after means that it happens later. For example, I usually have breakfast before work, She always checks her emails before a meeting, and We went for a walk after dinner. We can also use them with complete clauses: I turned off the lights before I left the house, or They went home after the concert finished. These expressions are particularly useful when describing routines, schedules and sequences of events.

The preposition during tells us that something happens within a particular period or event. For example, Nobody spoke during the film, It rained during the night, and We met some interesting people during our holiday. Notice that during is followed by a noun or noun phrase, such as the lesson, the meeting or the summer. It does not tell us how long something lasted. Compare I fell asleep during the film with I slept for two hours. The first sentence identifies the event in which something happened, while the second tells us the duration.

Until, sometimes shortened to till, tells us that an action or situation continues up to a particular moment. For example, The shop stays open until eight o’clock, We waited until midnight, and She worked until Friday. The important idea is that the situation continues and then reaches an endpoint. You can also say Stay here until I come back or Don’t open the door until the teacher arrives.

Another very useful preposition is by, especially when talking about deadlines. It means that something must happen no later than a particular time. For example, Please send me the report by Friday, You must be home by ten, or The work should be finished by the end of the month. Be careful with the difference between by and until. If someone says I’ll work until six, the work continues up to six o’clock. But if someone says I’ll finish the work by six, the work may finish earlier, but it must be completed no later than six.

Finally, from and to are often used together to describe the beginning and end of a period. For example, The museum is open from nine to five, I worked in London from 2018 to 2022, and The festival runs from Monday to Sunday. The expression gives us two points in time and describes the period between them.

These prepositions allow us to describe time much more precisely. We can explain that something happened before another event, after a meeting or during a journey. We can say that an activity continued until midnight, that a task must be completed by Friday, or that an event lasts from Monday to Thursday. Learning these distinctions will help you understand schedules, tell stories and describe the order and duration of events more naturally.