The document summarizes the proper uses of the prepositions "in", "on", and "at" for expressing times and dates in English. It provides examples of when to use each preposition for things like days, dates, times of day, periods of time, seasons, and the future. It then has an exercise for the reader to fill in the correct preposition for 16 different time and date phrases.

1. IN / ON / AT (TIME)
 Usamos "AT" para:
At + hora del día
At 6:30 - A las 6:30
At 7 o'clock - A las siete
At dawn - Al amanecer
At lunchtime - Al mediodía
At midnight - A la medianoche
At + día festivo
At Christmas - En Navidad
At Easter - En Pascuas
At New Year - En Año Nuevo
At Lent - En Cuaresma
At Holy Week - En Semana Santa
At + ciertas expresiones
At the moment - En este momento
At the weekend - El fin de semana
At that time - En ese tiempo
At night - A la noche
At noon - Al mediodía
 Usamos "ON" para:
On + día
On Monday - El lunes
On Tuesday - El martes
On Wednesday - El miércoles
On Thursday - El jueves
On + día + parte del día
On Friday morning - El viernes por la mañana
On Saturday afternoon - El sábado por la tarde
On Sunday evening - El domingo a la noche
On + fechas
On Christmas Day - El día de Navidad
On July 4th - El 4 de Julio
On December 31st 1966 - El 31 de diciembre de 1966
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2.  Usamos "IN" para:
In + partes del día
In the morning - Por la mañana
In the afternoon - Por la tarde
In the evening - Por la noche
In + meses
In January - En enero
In February - En febrero
In May - En mayo
In + años
In 1966 - En 1966
In 1845 - En 1845
In the 1960s - En los sesenta
In + estaciones del año
In summer - En verano
In spring - En primavera
In fall / autumn - En otoño
In winter - En invierno
In the early summer - Al comenzar el verano
In + largos períodos
In the 19th century - En el siglo 19
In the past - En el pasado
In the future - En el futuro
In the Middle Ages - En la Edad Media
In the Stone Age - En la Edad de piedra
In + referencia al futuro
I will be there in two days - Estaré allí en dos días
In nine months - En nueve meses
In five minutes - En cinco minutos
In three years - En tres años
In seven hours - En siete horas
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3. 1. Fill in the gaps with the correct time preposition in / at / on.
1. What are you doing _____ Christmas?
2. I usually stay at home _____ the evening.
3. She arrives _____ Monday.
4. I love walking _____ night.
5. We often go to the country _____ weekends.
6. I will be free _____ four o'clock.
7. I do yoga _____ Fridays.
8. See you this evening _____ half past seven.
9. I don't like getting up _____ the morning.
10. I was born _____ July.
11. Peter is playing tennis _____ Sunday.
12. My brother's birthday is _____ the 5th of November.
13. My birthday is _____ May.
14. We are going to see my parents _____ the weekend.
15. I don't like walking alone in the streets _____ night.
16. What are you doing _____ the afternoon?
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