關於present perfect tense

1.
Present Perfect Tense 的用法：

a) 表示剛完成的動作
e.g. I have just finished my homework.

b) 表示未有指明時間而已過去的動作
e.g. I have bought a car.

c) 表示在一個未過去的時段內發生的動作
e.g. I have called May three times this morning. ( 說話的時候仍然是上午 )

d) 表示在過去開始並維持至現在的動作
e.g. I have lived here for five years. ( 五年前開始住在這裡，現在仍住在這裡 )

e) 談及個人經歷
e.g. I have been to Japan twice. ( 到目前為止去過兩次，將來可能會再去 )

Simple Past Tense 只用以敘述過去發生的事件
e.g.
a) I finished my homework a few minutes ago.
b) I bought a car last week.
c) I called May three times this morning. ( 說話的時候已經過了上午 )
d) I started to live here five years ago.
e) I went to Japan last year.

2.
與 this morning/afternoon/week/month/year or today 連用的情況：
用 Present Perfect Tense 還是 Simple Past Tense 取決於說話的時間
e.g.
( 說話時間是 2p.m., 即仍然是下午 )
I have seen Amy this afternoon.

( 說話時間是 6p.m., 即已過了下午 )
I saw Amy this afternoon.

與 always/never/ often 連用表示慣性動作
e.g.
I have always got up early in the morning.
I have never been late for school.

3.
Present Perfect Tense 可表示最近發生的動作，其影響仍然存在

e.g.
a) My car has broken down. ( 汽車很可能仍在修理 )
b) My car broke down. ( 汽車很可能已修理，能正常運作了 )

例子a) 的情況跟現在有直接關係，所以用 Present Perfect Tense，而不用 Simple Past Tense

4.
因為 this year 還未過去

5.
"She has been an air hostess" 用 Present Perfect Tense，是因為她現在還是一位空姐

"Since she left school" 用 Simple Past Tense，是因為她完成學業是過去的事件，跟現在沒有直接關係

6.
因為這是談及個人經歷的情況

如果純粹敘述過去發生的事件，則用 Simple Past Tense
She went to London last month.

7.
Present Perfect Tense 和 Simple Past Tense 均可

a) Ed Prior has won his first gold medal.
( 很可能是最近發生，並且他仍然充滿勝利的喜悅 )

b) Ed Prior won his first gold medal.
( 純粹敘述過去發生的事件，不過省去時間會令句子的意思不完整 )

8.
Present Perfect Tense
因為這是談及個人經歷的情況

9.
When 一般情況下不會與 Present Perfect Tense 連用

When 與 Simple Present Tense 連用：
When I grow up, I want to be a nurse.

When 與 Simple PastTense 連用：
When I saw my teacher, I greeted her.

10.
I have been at school since nine o'clock.
從九時起我一直在學校。 ( 我現在仍然在學校 )

I have gone to school.
我上學去了。 ( 我現在已經離開學校了)

1. past: happened in the past, known time of occurrence
perfect: happened in the past, unknown time of occurrence
2. those key words u mentioned are usually associated with past tense (because the time is known: this morning, etc), while perfect tense is usually associated with 'for how long'/'since when'
3. past: only significant in the past, but the impact doesn't affect the situation now
perfect: happened in the past but the incident still has impact/significance nowadays
4. twice=for two times, the stress is not on 'this yr', but he has gone there 'for two times' (or simply two times/twice is ok)
5. yes
6. 佢曾經去過, the main point this sentence wants to bring out is 'she has once been there', but not '佢去左'
7. both are acceptable. if use past: he won the medal. then it simply mentions that he won the prize in the past, not now, it's past. if use perfect: he has won the medal. that means 佢曾經攞過.
8. probably perfect. i have gone. (similar to no.4)
9. no. it depends on wt the sentence is trying to say. e.g. i have already finished my work when you came home. 你來之前我已經搞店.
10. have been at school: in school
have gone: leave school
so, have been at school since 9: 由9點開始我就係學校
have gone to school since 9: (weird...) 由9點開始我就出發去學校 (?)/ 出門日去學校 (?)

2010-04-25 21:57:22 補充：
出門口*

重點是在第三條：
我份notes有句話"for action which have recently finished and their result are
visible in the present"啲時候係用present perfect tense,甘點解又唔用past
tense?因為都過去左..你的筆記已很清楚地交代了在甚麼時候用present perfect tense。要記得，選擇用那一個時態，是在乎於說話者想表達的意思，而非因為句子中有某個字。當你想說一件在過去發生但持續至現在的事情時，或剛剛完成的事情，你就用present perfect tense；但若你想說那是完仕過去的事情，你就會用past tense。

例如：（第十條）
I have been at school since nine.
To be 是一個可以持久的動作，當你用present perfect tense寫這句時，你是說從九時開始，我一直都在學校內。
I was at school at nine.
用過去式寫，你是指在九時的那一刻，你在學校內。你現在可能仍在校內，也可能在其他地方。這一點在句中沒有交代。
I went to school at nine.
若你選用的動詞是to go，那麼在這句就丕可以用present perfect tense，因為「去」的動作只可以在一刻時發生。

（第六條）
She has been to London.
若你把句子寫成 She was in London，那就只是寫某一次她在倫敦，一個在過去發生並已完成的事情。可是，你想表達的是她「曾經」到過倫敦，那就要用present perfect。

（第七條）
To win his first gold medal 一定是在過去發生，因為在比賽之前不能知道誰會奪得金牌，而「他的第一面金牌」也指他贏其他比賽的金牌。所以，時態一定不會是present perfect。

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