Correct Usage of 'Since' and 'For' in English Grammar: A Detailed Analysis

When writing or speaking in English, the correct use of prepositions can significantly impact the clarity and accuracy of your communication. This article focuses on one such common confusion: the usage of 'since' and 'for' when indicating a period of time. Specifically, we will explore the correct phrases 'I have been ill for the last ten days' and 'I have been ill since the last ten days', and why one is correct and the other is incorrect.

Understanding the Difference Between 'Since' and 'For'

The prepositions 'since' and 'for' are both used to indicate time, but they do so in different ways. 'Since' is used to denote a specific point in the past from which a process or event has been ongoing. 'For,' on the other hand, is used to indicate a duration or a period of time. Here's a more detailed breakdown:

For - Indicating Duration

The correct phrase is 'I have been ill for the last ten days.' The use of 'for' shows that the illness has been ongoing for a ten-day period. This preposition indicates a duration and can be followed by a period of time.

Example:

She has been working at the company for five years.

Since - Indicating a Starting Point

On the other hand, 'since' indicates a specific point in the past. When using 'since,' it's generally followed by a specific event, date, or time. If the subject is ongoing from that point, 'for' is often used to describe the duration.

Example:

I have been working at the company since April 2022.

Why 'I have been ill since the last ten days' is Incorrect

The phrase 'I have been ill since the last ten days' is incorrect because 'since' is not the appropriate preposition to use here. As mentioned, 'since' is used to indicate a specific point in the past. In this case, 'the last ten days' is not a specific point; it is a duration. Therefore, 'for' should be used instead.

Conclusion

In summary, the correct phrase is 'I have been ill for the last ten days.' This usage properly indicates that the illness has lasted for a ten-day period. The phrase 'I have been ill since the last ten days' is incorrect because 'since' does not suit the context of a duration. Understanding the appropriate usage of 'since' and 'for' can significantly enhance the clarity of your English writing and speech.

Key Points to Remember:

S-ince → point of time. For → period of time. Use 'for' when indicating a period of time. Use 'since' when indicating a specific point in the past.

Always remember to choose the correct preposition based on the context and the specific aspect of time you are indicating.