英语单词大师：Present Perfect Tense

 AA: I'm Avi Arditti with Rosanne Skirble, and this week on Wordmaster: practice makes perfect.

RS: With us from Los Angeles is English teacher Lida Baker¹ to explain a part of grammar that makes English learners tense.

AA: It's the verb tense known as the present perfect. First of all, Lida says don't be misled by the archaic² meaning of perfect.

LIDA BAKER: "In Latin it has to do with whether something is complete or incomplete³. In linguistic⁴ terms, the present perfect tense is pretty unique, pretty unusual, and it's something that students always wrestle⁵ with. So the present perfect tense is formed by using the auxiliary⁶ verb 'have' and the past participle of a verb. And if that terminology⁷ is a little bit too confusing, I'll just give you some simple examples: 'I have eaten breakfast already' or 'he has seen that movie three times.' So the present perfect is that form that uses either have or has, followed by the past participle form of the verb."RS: "That's the form. Now we need to focus on how you use it."LB: "Well, that's the interesting part. One of the basic meanings of the present perfect tense is to talk about things that began in the past and continue up to the moment of speaking. An example of that would be something like 'I have lived in Los Angeles for 25 years,' 'she's been a teacher since she was 25 years old.' So cases where the action began in the past and continues until this moment, that's one way in which we use the present perfect tense.

"Cases like that do not give students difficulty, though. Maybe it's because with that meaning we often pair the sentence with a phrase that starts with 'for' or 'since.' So, 'for 16 years' or 'since I was 12 years old,' those sorts of things are not hard for students to learn.

"We use the past tense when something occurred in the past and we know exactly when it happened. So, 'I visited my grandmother three days ago' or 'he graduated from college last month.' When the time that the event occurred is given, then according to the rules, we have to use the past tense, OK?

"In contrast to that, if something occurred in the past but there is no specific time stated, that's when we use the present perfect. So we would say something like 'I have finished my homework,' 'I've seen that movie' and so on. And, according to the strict rules of grammar, if you take a sentence like 'I've seen that movie' and you use it with the word 'yesterday,' in American English strictly⁸ speaking that sentence is incorrect. It would be wrong to say 'I have seen that movie yesterday.' But in reality -- "RS: "Instead you would say 'I saw that movie yesterday.'"LB: "That's right."AA: "Now, like in the homework example, if a kid comes up to you and says 'I have -- I've finished my homework,' they're talking about like in the past few minutes as opposed to 'I finished my homework -- "RS: "Two days ago."AA: " -- two days ago,' or something like that, is that what you're ... "LB: "That could be one explanation. But another explanation could be that the student is handing me his paper, you see. So this is how the relevance⁹ to the present is established. He says, 'I've finished my homework, and here it is.' You see? Sometimes the link is established by means of the context¹⁰, OK? Sometimes we've had some kind of an experience in the past that has relevance for the present, in a sentence something like, 'I've used that machine lots of times, so I can teach you or help you with it now.'

"Another way that this relevance to the current moment is established is if something has happened in the past, but there's a good probability¹¹ that it might happen again. So a sentence like, 'I've been to the Hollywood Bowl twice this summer.' The Hollywood Bowl is a large outdoor concert arena¹² here in Los Angeles. So, 'I've been to the Hollywood Bowl twice this summer ... '"RS: And the use of the present perfect indicates she might go again -- although at the present moment, Lida is busy with a new group of students.

AA: Lida Baker teaches in the American Language Center at the University of California, Los Angeles. All her previous lessons with us are on our Web site, voanews.com/wordmaster.

RS: And if you'd like to send Avi and me an e-mail, the address is [email protected]. With Avi Arditti, I'm Rosanne Skirble.

1 baker   

n.面包师

参考例句：

• The baker bakes his bread in the bakery.面包师在面包房内烤面包。
• The baker frosted the cake with a mixture of sugar and whites of eggs.面包师在蛋糕上撒了一层白糖和蛋清的混合料。

2 archaic   

adj.(语言、词汇等)古代的，已不通用的

参考例句：

• The company does some things in archaic ways,such as not using computers for bookkeeping.这个公司有些做法陈旧，如记账不使用电脑。
• Shaanxi is one of the Chinese archaic civilized origins which has a long history.陕西省是中国古代文明发祥之一，有悠久的历史。

3 incomplete   

adj.不完全的，不完善的

参考例句：

• The building was left incomplete.那座楼没有完工就停下来了。
• His novel was incomplete when he died.他死的时候他的小说没有写完。

4 linguistic   

adj.语言的，语言学的

参考例句：

• She is pursuing her linguistic researches.她在从事语言学的研究。
• The ability to write is a supreme test of linguistic competence.写作能力是对语言能力的最高形式的测试。

5 wrestle   

vi.摔跤，角力；搏斗；全力对付

参考例句：

• He taught his little brother how to wrestle.他教他小弟弟如何摔跤。
• We have to wrestle with difficulties.我们必须同困难作斗争。

6 auxiliary   

adj.辅助的，备用的

参考例句：

• I work in an auxiliary unit.我在一家附属单位工作。
• The hospital has an auxiliary power system in case of blackout.这家医院装有备用发电系统以防灯火管制。

7 terminology   

n.术语；专有名词

参考例句：

• He particularly criticized the terminology in the document.他特别批评了文件中使用的术语。
• The article uses rather specialized musical terminology.这篇文章用了相当专业的音乐术语。

8 strictly   

adv.严厉地，严格地；严密地

参考例句：

• His doctor is dieting him strictly.他的医生严格规定他的饮食。
• The guests were seated strictly in order of precedence.客人严格按照地位高低就座。

9 relevance   

n.中肯，适当，关联，相关性

参考例句：

• Politicians' private lives have no relevance to their public roles.政治家的私生活与他们的公众角色不相关。
• Her ideas have lost all relevance to the modern world.她的想法与现代社会完全脱节。

10 context   

n.背景，环境，上下文，语境

参考例句：

• You can always tell the meaning of a word from its context.你常可以从上下文中猜出词义来。
• This sentence does not seem to connect with the context.这个句子似乎与上下文脱节。

11 probability   

n.可能性，可能发生的事，概率

参考例句：

• The probability that it will rain today is high.今天下雨的可能性很大。
• He must calculate the probability of failure.他必须计算一下失败的概率。

12 arena   

n.竞技场，运动场所；竞争场所，舞台

参考例句：

• She entered the political arena at the age of 25. 她25岁进入政界。
• He had not an adequate arena for the exercise of his talents.他没有充分发挥其才能的场所。