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"He hasn't travelled overseas before." Now before I give you some more examples let's talk about when to use the past simple tense and the present perfect tense because this is often the confusing part about this tense.
他之前没有出过国。好了，我就不举更多的比方了。咱们先来看看啥时分大约用”一般曩昔时“ 而啥时分大约用”如今结束时“，因为这两个时态是比照令人困惑的。
To answer this question, you need to think about time, finished time and unfinished time. So think about last week — that's a good example of finished time.
想要清楚白这两个时态的差异，你需要区别句中的”时刻段“，现已结束的时段和没有结束的时段。比方“上星期”这个时刻段，就是极好的一个比方标明这个时刻段现已结束了。
Last week is finished, it's over. But what about this week?
上星期是现已结束了。那么“本周”呢？
Is this week finished? No, not yet.
本周的时刻段结束了吗？不，还没结束。
That's an example of unfinished time. There is still more of this week to come, it's not finished yet.
那么“本周”就是没有结束时刻段的一个极好的比方了。说话人在说“本周”的时分可以在周一或周五，一周七天的时刻还没有结束，还在持续。
Yesterday, last week, last month, last year, 1991. These are all examples of finished time.
昨日、上星期、上个月、上一年、1991年这些时刻段。这些都是现已曩昔了的时刻段。
Time that is complete. When you're talking about a time period that has finished — like these — you need to use the past simple.
标明时刻现已完全结束了。当你描绘一个现已结束了的时期包括这些现已结束了的时刻段，你就要用一般曩昔时。
But when you're talking about a time period that is unfinished, like today, this week, this year, this month, use the present perfect tense. So let's compare some examples.
但假定你是描绘一个还没有完全结束的时刻段，比方说“今日”、“这一周”、“本年”、“这个月”，就要用如今结束时。那么咱们来比照一下下面两个例句。
"Last month, I visited my brother three times." "This month I have visited my brother twice."
上个月，我探望了我的兄弟三次”这个月，我探望了我的兄弟两次。
But the month isn't finished yet and I may visit him again. Try an example with me.
“这个月”是还没有完全结束的时刻段，我还可以再次探望我的兄弟。和我一同再看个例句：
"He borrowed my car yesterday." So this sentence is in the past simple.
他昨日借了我的车。这个是一般曩昔时。
It's finished time. Now, try to change it to the present perfect yourself.
借车的动作现已结束了。如今，测验将一般曩昔时变换为“如今结束时”。
What do you need to do? Two things.
你该怎么做呢？首要有两点。
You need to add the auxiliary verb — "he has" "has" not "have" — it changes because our subject is he.
你先要添加一个辅佐动词“he has”。主语“he”是第三人称奇数，要用“has”不是“have”啊。
"He has borrowed my car today" or this week. We need to change the time expression too for our sentence to work in the present perfect tense.
他今日借了我的车，“今日”也可用换为“这个星期”。由一般曩昔时变换为如今结束时，咱们就需要变换语句中时刻的表达方法。
It must be unfinished time. Okay so those were all examples of the present perfect in positive sentences.
这个时刻段有必要是没有结束的。好的，这些都是如今结束时的必定方法。
But what about negative forms? Of course, we need to add "not" to our sentence, to our structure.
那么否定方法呢？很简略，只需在否定语句里参加否定词”not“(没有/不)。
Subject plus "have" or "has" plus not and then our past participle verb. So compare these sentences.
格局是：主语 + have/has +not +主动词（动词是曩昔分词方法）比照一下这两个语句。
"Last month, I visited my brother three times." "This month, I haven't visited him at all."
上个月，我探望了我的兄弟三次。这个月，我还没探望过我的兄弟。
But the month isn't over, yet. I may still visit him.
记住，这个月并没有结束哦。所以我可以还会探望我的兄弟。
Again, see that this structure is usually contracted in spoken English. "Haven't"
重申一下：口语中，这些语句里的助动词一般会被省掉前半有些，与主语缩写。还没有。
This is the most common way to contract the negative form but you may also hear people say "I've not visited him." Both ways are acceptable but you can't contract all three words together.
当然，你可以还听过别人说的另一种缩写的方法，如：“I've not”，我还没造访过他。以上两种缩写方法都是可以的。可是不能将三个词语简缩在一同，
I'ven't. You can't do that! It's one contraction, or the other.
如：“I'ven't”。这样的缩写方法是差错的！只能是二者择其一。
Another example, "He ate so much yesterday! Notice the time word that we're using.
再看例句：他昨日吃得太多了！留心里边的时刻词的运用。
So in present perfect negative, we can say "He hasn't eaten a lot today" but there is still more day so he could eat more food. One more example. "They were at school yesterday."
那么在如今结束时的否定句里，可以这样说：他今日没有吃许多。可是今日的这个时刻段还没有结束哦，在“今日”结束前，他可以还会持续吃更多。再比方：他们昨日在学校。
In the present perfect, "They haven't been at school all morning." But the day's not finished yet and they may arrive in the afternoon.
用“如今结束时”来表达的话，大约是：他们从早上到如今还没来学校。“这一天” 还没有结束，他们可以会鄙人午到学校。
Of course, you need to ask present perfect questions too, right? As with all English question forms, our auxiliary verb needs to change position.
当然了，你还会问到“如今结束时”的疑问句格局，对吧？一切时态的英语疑问句格局都是将句中的助动词移到语句前面来。
So we have "have" and "has", our subject and our past participle verb. "Has he cleaned the bathroom?"
其格局为：Have
/Has（助动词） +主语 + 主动词（动词是曩昔分词方法）。他打扫清洁间了吗？
"Have you eaten enough?" "Has it rained today?"
你吃饱了吗？今日下雨了吗？
"Have they finished yet?" Now compare these two questions.
他们结束（结束）了吗？如今来比照一下这两个疑问句。
"Did you go to Thailand last year?" This is a past simple question so the auxiliary verb "do" takes the tense it becomes "did" but now compare it to "Have you been to Thailand?"
你上一年去泰国了吗？这个是一般曩昔时的疑问句，所以助动词“do”变成了曩昔式“did”，再看看这句话：你去过泰国吗？
This means at any time in the past, it's your life experience, but of course, you're still alive, so you may go in the future. The difference is the time reference.
这个问句表述的是在曩昔的任意一个时刻段的某个日子阅历。因为你还活得好好的，所以“你”可以会在将来的某个时刻去泰国。两个疑问句的要害不一样点就是时刻的表述。
There is a lot to think about when using the present perfect tense, right? But I hope that this lesson made everything a little easier, especially the basics.
是不是感触这个“如今结束时”仍是有许多不太好掌控的当地呢？不管怎么说，我期望我们观看完这节课能更简略地运用这个时态，特别是最根柢的常识点。
If you're clear on the basics, it's a good thing. Make sure that you're subscribed to the mmmEnglish Channel because the next few lessons that I make will help you to practise using the present perfect tense.
假定你弄理解了最根柢的规划和格局，抵挡它就手到擒来了。记住订阅 mmmEnglish 频道哦，因为接下来我录制的几节课程可以协助你操练和使用如今结束时句型。
You don't want to miss them! Just click that red subscribe button just there.
你大约不想错失这几节课程吧？所以，请从速点击屏幕右下方的赤色按钮“subscribe”，就在右下方。
You can watch more mmmEnglish lessons right here or you can improve your pronunciation and your English speaking skills by practising with the imitation technique right here! Thanks so much for watching and I'll see you in the next lesson.
你还可以观看更多的英语课程视频，咱们的页面上还有许多英语仿照课程，经过观看视频和仿照操练可以改进你的英语发音或前进你的英语口语技巧。非常谢谢我们的观看，咱们下节课再会。
Bye for now!
拜拜！
Notes
1.jog sb's memory to make someone remember something 引发回想
The police showed him a photo to try to jog his memory about what hadhappened on the night of the robbery. 警方给他看了一张相片，想让他记起掠取的当晚发生了啥。
2.contract verb /kntrkt/ contract verb (BECOME SMALLER)
to make or become shorter or narrower or generally smaller in size （使）减小；缩短
In spoken English, "do not" often contracts to "don't". 在英语口语中，do not 常常缩略成 don't。
3.subscribe verb /sbskrab/
to pay money to an organization in order to receive a product, use a service regularly, or support the organization 订阅，订购（产品）
2.3 million people subscribe to this online music service. 有230万人订购了这个在线音乐效能。
