现在完成进行时和现在完成时的比较
The present perfect continuous form is often confused with the present perfect. Indeed, there are many instances in which the present perfect continuous can be used as well as the present perfect. For example:
现在完成进行时和现在完成时经常容易被混淆。事实上，这两者在很多种情况下都可以互换使用。
I've worked here for twenty years. OR I've been working here for twenty years.
我已经工作了20年了。
I've played tennis for twelve years. OR I've been playing tennis for twelve years.
我打网球已经12年了。
The main emphasis in the present perfect continuous is on expressing how long the current activity has been happening.
现在完成进行时主要是强调，现在进行的某个活动一直都在持续着。
It's best to stress that the present perfect continuous form is used for shorter periods of time to express how long that particular action has been taking place.
我们有必要强调一下，现在完成进行时指的是短时间内，用来表示特定的动作发生的时长。
I've been writing for thirty minutes.
我已经写了30分钟了。
She's been studying since two o'clock.
她从两点开始就在学习了。
In this manner, you'll help students understand that the present perfect continuous is used to express the length of a current action. Compare this to cumulative length for which we tend to use the present perfect, although the present perfect continuous can be used.
通过这种方式，你可以帮助学生们了解到，现在完成进行时是用来表示现在发生的动作持续了多久。要是表示累计的时长，我们一般使用现在完成时态，虽然现在完成进行时也同样适用。
INTRODUCING THE PRESENT PERFECT CONTINUOUS
现在完成进行时的介绍
Start by Speaking about the Length of Current Actions
现在发生的动作的持续时间
Introduce the present perfect continuous by asking students how long they've been studying in the current class on that day. Extend this to other activities. It's a good idea to use a magazine with photos and ask questions about how long the person in the photo has been doing a particular activity.
要介绍现在完成进行时，我们可以问问学生他们当天在班上学习了多长时间。然后延伸到其他的活动。用含图片的杂志，并询问图片中的人进行一个特定的活动多久是一个不错的主意。
Length of Current Activity
现行活动的时长
Here's an interesting photo. What's the person doing? How long has the person been doing XYZ?What about this one? He looks like he's getting ready for a party. I wonder if you can tell me how long he's been getting ready for the party.
这儿有一张有趣的图片。图片里的人在做什么？这个人做某件事持续了多久？这个呢？他看起来像是要准备参加一场聚会。我想知道，你能不能告诉我他为这个聚会准备了多久？
Result of Activity
活动结果
Another important use of the present perfect continuous is to explain what has been happening that has caused a present result.
现在完成进行时的另一个重要的用法就是，解释导致现在结果的原因。Stating results and asking questions are effective in teaching this use of the form.
陈述结果，并提出问题，这种现在完成进行时的教学方法十分有效。
His hands are dirty! What has he been doing?
他的手真脏啊！他一直都在干嘛？
You're all wet! What have you been doing?
你浑身都湿透了！你一直都在做什么？
He's tired. Has he been studying for a long time?
他累了。他学习了很长时间吗？
PRACTICING THE PRESENT PERFECT CONTINUOUS
现在完成进行时的练习
Use a timeline to illustrate the two principal uses of the present perfect continuous. With such a long string of helping verbs, the present perfect continuous can be a bit confusing. Make sure that students understand the construction by providing a structural chart like the one below:
用一个时间轴来解释现在完成进行时的两种主要用法。通过一系列的助动词，现在完成进行时可能会让你有点眼花缭乱。你可以通过绘制和以下内容类似的图表来帮助学生们理解整个结构。
Subject + have + been + verb(ing) + objects
主语+have+been+动词ing+宾语
He has been working for three hours.
他已经工作了三小时了。
We haven't been studying for long.
我们学习的时间并不长。
Repeat for the negative and interrogative forms as well. Make sure students understand that the verb 'have' is conjugated. Point out that questions are formed with "How long ..." for the length of an activity, and "What have you ..." for explanations of current results.
否定形式和疑问形式也是如此重复。确保学生们能了解，动词have的词形变化。指出由How long提出的询问活动时长的问题，以及由What have you…提出的对现行结果的解释。
How long have you been sitting there?
你在这里坐了多久了？
What have you been eating?
你一直都在吃什么？
Comprehension Activities
理解活动
It's a good idea to compare and contrast both the present perfect and present perfect continuous when first teaching this tense.
在第一次教授这种时态时，将现在完成时和现在完成进行时进行比较是一个不错的方法。
At this point in their studies, students should be able to handle working with two related tenses. Use lessons that focus on the differences to help them distinguish usage. Quizzes testing present perfect or perfect continuous use also help students become familiar with the two tenses. Present perfect and continuous dialogues can also help with practicing the differences. Also, make sure to review non-continuous or stative verbs with students.
在学习的过程中，学生们应该学会处理这两种相关联的时态。通过讲解二者区别的课程，可以帮助学生们了解他们用法的不同。现在完成时和现在完成进行时的测验也能够帮助学生们熟悉这两种时态。关于这两种时态的对话也可以帮助学生区别二者的不同。另外，一定要和学生对不连续动词或静态动词进行回顾。
Challenges with the Present Perfect Continuous
现在完成进行时的难点
The main challenge students will face with the present perfect continuous is understanding that this form is used to focus on shorter lengths of time. I find it's a good idea to use a common verb such as 'teach' to illustrate the difference. For example:
学生们在学习现在完成进行时时，面临的最主要的难点就是弄明白，这种形式是用来对一个短的时间段进行强调。我发现，可以利用共同的词汇，例如have来阐释二者的区别。例如：
I've taught English for many years. Today, I've been teaching for two hours.
我已经教了许多年的英语了。今天，我已经上了两小时的课了。
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