Using Prepositions Correctly to Specify Time
Prepositions are a class of words that indicate grammatical and semantic relationships, often of a spatial or temporal nature. A preposition is usually combined with a noun, pronoun or noun phrase, which is referred to as the preposition’s complement or object. The phrase as a whole, including a preposition and its complement, is a prepositional phrase. Prepositional phrases act as adverbs or adjectives to modify verbs, adverbs or adjectives. Although prepositions are non-inflected, which is to say their forms do not change based on grammatical function, it can at times be difficult to choose the right preposition and achieve appropriate phrasing around it.
As the name ‘preposition’ suggests (pre-positioned), prepositions generally precede their complements, and for some authors they always should. However, in questions and less formal English, such as that used in speech, prepositions can become stranded, which means that they appear in positions other than before their complements. “Which plane did you fly on?’ is an example of the kind of stranding that frequently occurs in English speech. In formal scholarly prose a better choice would be “On which plane did you fly?’ but some readers and writers now find this sort of construction awkward and will prefer the stranded preposition even in academic and scientific writing.
One of the most common uses of prepositions in English sentences is to enable the inclusion of specific information about time in order to establish a temporal relationship between the complement of a preposition and what it modifies. When referring to specific moments or points in time the prepositions ‘at,’ ‘in’ and ‘on’ are used. ‘At’ is the right choice if you need to specify a time of day, such as ‘I start work at 8 a.m.’ or ‘I drive to the library at three o’clock.’ ‘Dawn,’ ‘noon,’ ‘night’ and ‘midnight’ are also used with the preposition ‘at,’ as in ‘She wakes up at dawn’ and ‘He likes to read at night.’ For other parts of the day, however, ‘in’ is used instead of ‘at,’ as it is in ‘She prefers to walk in the morning’ and ‘They usually write in the afternoon.’ ‘In’ is also used when referring to months, seasons and years, so ‘There is usually a lot of snow in January,’ ‘The weather is much warmer in the summer’ and ‘My first article was published in 1998’ are all correct. When referring to a specific day, ‘on’ is the appropriate preposition, as in ‘I visit the library on Saturday, but he usually goes on Sunday’ and ‘The concert is on the 23rd of February.’
To indicate extended time, a number of different propositions are used, such as ‘between,’ ‘by,’ ‘during,’ ‘for,’ ‘since’ and ‘within’ (or sometimes just ‘in’). The following examples demonstrate their correct use: ‘The show was playing in town between Christmas and Easter,’ ‘It has to be finished by tomorrow,’ ‘He watches soap operas during the day,’ ‘I am on vacation for two whole months,’ ‘She has been missing since last week’ and ‘The research has to be finished within a month,’ which might be alternatively worded as ‘The research has to be finished in a month.’ ‘From’ is also used when expressing an extended period of time, but it is accompanied by ‘to’ or ‘until’ for clarity. ‘The study focussed on events that occurred from the beginning of 2011 to the end of 2013’ is an example of the first, while ‘Our Christmas tree was up from 1 December to 31 December’ shows the use of the second.
