Lesson

For and since, when...? How long...?

Time questions

≈ 15 min 8 block(s)

Text

For and since, when...? How long...?

This lesson explains how to use for and since to talk about duration and starting points, and how to ask and answer questions with when and how long. We focus on the common structures used with the present perfect and present perfect continuous to describe actions or states that continue up to now.

  • Use for + a period of time (for two weeks, for 3 years).
  • Use since + a specific starting point (since Monday, since 2018).
  • Ask 'When...' to find a starting point and 'How long...' to ask about duration.

Table

Usage Examples: for / since / when / how long

Expression Use Example
for Duration (period of time) I have worked here for five years.
since Starting point (specific time) She has lived in Paris since 2016.
When...? Ask about a specific time or date When did you start this project?
How long...? Ask about duration How long have you worked on this report?
Present perfect Action started in past and continues to now They have managed the account since January.
Present perfect continuous Emphasizes duration of ongoing action I have been working here for three months.

Tip

Key rule: For = duration, Since = starting point

Remember the difference and the verb tense:

  • Use for + a period (for three hours, for two months).
  • Use since + a specific start time (since 9 AM, since March).
  • Combine with present perfect (have/has + past participle) or present perfect continuous for ongoing situations.

If you can replace the phrase with a duration (e.g., 'three years'), use for. If you replace it with a point in time (e.g., '2018'), use since.

Example

Examples in context

I have worked at the company for six years.

She has been the project manager since April.

When did you start the training program?

How long have you been responsible for that client?

Tip

Common mistakes to avoid

Watch out for these universal errors learners often make:

  • Using since with a duration (e.g., 'since three years' — incorrect).
  • Using for with a specific start point (e.g., 'for 2019' — incorrect).
  • Mixing tenses: using simple past instead of present perfect for actions continuing to now.
  • Confusing 'when' and 'how long' questions — 'when' asks for a point in time, 'how long' asks for a duration.

Always check whether you need a duration (for) or a starting point (since), and choose the correct tense.

Quiz

Choose the correct sentence:

Hint: Focus on whether the phrase is a duration or a specific start point.

Quiz

Complete: How long _____ at this company?

Hint: Think about the form used to ask about duration up to the present.

Quiz

Choose the best answer to: 'She started the position in 2019.' — 'How long has she been in the position?'

Hint: Decide whether the sentence needs a starting point (since) or a duration (for).

Key Points

GrammarPoint

for

preposition CEFR A2 //fɔːr//

Used with a period of time to indicate duration.

We have an agreement for three years.

GrammarPoint

since

preposition CEFR A2 //sɪns//

Used with a specific starting point in time.

She has been in sales since January.

Expression

how long

expression CEFR B1 //haʊ lɒŋ//

A question phrase used to ask about duration.

How long have you managed this account?

GrammarPoint

present perfect

grammar term CEFR B1 //ˌprɛzənt ˈpɜːrfɪkt//

A tense (have/has + past participle) used for actions that connect past and present.

They have completed the audit since March.

Vocabulary

duration

noun CEFR B1 //djʊəˈreɪʃən//

The length of time that something lasts.

The duration of the course is six weeks.

GrammarPoint

present perfect continuous

grammar term CEFR B2 //ˌprɛzənt ˈpɜːrfɪkt kənˈtɪnjʊəs//

A tense (have/has been + -ing) used to emphasize the duration of an action that continues up to now.

I have been negotiating the contract for two weeks.