What is the Present Perfect Tense?
Before we add for 和 since, let’s remember the present perfect tense. It connects the past and the present.
- We form it with have 或 has + the past participle of the main verb.
- 例如，, I have seen that movie. 或 She has finished her homework.
When Do We Use 'For' with the Present Perfect?
我们使用 for to talk about a *period* or *duration* of time. It answers the question 'How long?'
- 使用 for with a length of time, like for two hours, for three days, for a long time, for many years.
- The action or situation started in the past and continues up to now.
For example:
- They have lived in Madrid for ten years. (The duration is ten years.)
- I have worked at Langcom for six months. (The duration is six months.)
When Do We Use 'Since' with the Present Perfect?
我们使用 since to talk about a *starting point* in time. It tells us *when* the action or situation began.
- 使用 since with a specific moment, like since 2015, since Monday, since I was a child, since last week.
- The action or situation started at that point and continues up to now.
For example:
- She has been a teacher since 2005. (The starting point is 2005.)
- We haven't eaten since breakfast. (The starting point is breakfast.)
What Verbs Are Common with For and Since?
Many verbs describe states or situations that often continue for a long time. These are very common with for 和 since.
- Common verbs include: live, work, know, have (meaning 'possess'), be, like, love, hate, enjoy, own.
- These verbs describe situations that are often true for an extended period.
For example:
- I've known him since high school.
- They've owned that car for three years.
How Do We Ask Questions with 'How long...?'
To ask about the duration of an action or situation that continues now, we use How long...? with the present perfect.
- 其结构如下： How long + have/has + subject + past participle...?
- You can answer these questions using either for 或 since.
For example:
- A: How long have you studied English?
- B: I've studied English for five years. (Duration)
- B: I've studied English since 2019. (Starting point)
| 功能 | 对于 | Since |
|---|---|---|
| Meaning | Duration (how long) | Starting point (when it began) |
| Example Phrase | for three hours, for many years | since 2010, since last week |
| Question | How long...? | Since when...? (less common, usually How long...?) |
| Example Sentence | He has slept for eight hours. | He has slept since 10 PM. |
示例
- I have lived in this city for ten years.
- She has worked at the company since January.
- We haven't seen them for a long time.
- He has been sick since last Tuesday.
- How long have you known your best friend?
- They have had that car for five months.
- I haven't visited my hometown since I was a child.
练习
西班牙语母语者常犯的错误
Using Present Simple Instead of Present Perfect
Spanish speakers often use the present simple with 'desde hace' or 'desde' to talk about ongoing actions, which is incorrect in English. You must use the present perfect.
- 错误： I live here for five years.
- 正确： I have lived here for five years.
- 错误： She works here since 2020.
- 正确： She has worked here since 2020.
Using Present Perfect for Finished Actions
Remember, the present perfect with for 或 since is for actions that *continue now*. If the action is finished, use the past simple.
- 错误： I have lived in New York for two years (from 2015 to 2017). (The period is finished.)
- 正确： I lived in New York for two years (from 2015 to 2017).
Confusing 'For' and 'Since'
This is a very common mistake. Remember the difference:
- For = duration (e.g., for three hours)
- Since = starting point (e.g., since 3 o'clock)
常见问题
What is the main difference between 'for' and 'since'?
The main difference is that for tells you the *length of time* (duration), like for two weeks. Since tells you the *starting point* in time, like since Monday. Both are used with the present perfect for actions that continue now.
Can I use 'for' or 'since' with other tenses?
Yes, but with different meanings. For example, you can use for with the past simple for a finished duration: I lived there for five years (but I don't live there now). You can also use since with the past simple to indicate a reason: Since it was raining, we stayed inside. However, for actions continuing to the present, the present perfect is usually required with for 和 since.
Are there any verbs that cannot be used with 'for' and 'since' in the present perfect?
Generally, verbs that describe short, completed actions (like arrive, start, finish) are less common with for 和 since in the present perfect, unless they are part of a continuous state. For example, you wouldn't say I have arrived for two hours. Instead, verbs that describe states or ongoing activities (like live, study, be) are typical.
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