上篇文章我们已经大致介绍了现在完成时的结构，今天我们来讨论两个常用句式和常用搭配词
How long have you...在对话中，我们经常用how long have you... 专门用来问对方“你完成......多久了？”，很抽象吧，直接上例子：
时间线索1：Jill is on holiday in Italy. She is there now.
Jill 正在意大利度假，她现在正在那儿。
时间线索2：She arrived in Italy on Monday.
她是星期一到达意大利的。
时间线索3：Today is Thurday.
今天是星期四。
而与how long相对应的，我们用for 和 since 来回答：
所以 how long has Jill been in Italy?
Jill 已经在意大利多久了呢？
--Jill has been in Italy for three days.(从星期二~星期四)
Jill已经在意大利三天了。
--Jill has been in Italy since Monday.(从到达当天算起)
Jill 从星期一已经在那了。
由上可以看出，用“for 一段时间”可以表示多久了。
用“since 开始的那一天”也可以表示多久了。
我们再来看个例子：
目前时间：2020年4月
How long have you bought your car?
--I have bought my car for 5 five years.
我已经买车5年了。
也可以说
--I have bought car since 2015.
我2015年就买车了。
而部分人会把 for 和 ago 混淆，但是，主要记住for与现在完成时搭配，ago与一般过去时搭配即可。
还是以Jill的事为例：
When did Jill arrive in Italy?
--She arrived in Italy three days ago.
How long has Jill been in Italy?
--She has been in Italy for three days.
Just & already & yet在现在完成时里还常见jsut，already，yet的搭配，到底怎么用？什么时候用？
Just=一小段时间之前，时间很短促，刚刚
Is Marco here?
--Yes, he has just arrived. 他刚刚到。
Are you hungry?
--No, we have just had our lunch.我们刚刚吃完午餐。
Is Tom still here?
--No, I'm afraid he has just gone. 他刚刚离开。
Already=在某人预料的情况之前已经完成
What time will Jill and Marco come?
--They've already arrived. 他们已经到了（在你的预料情况之前）
Paul, this is Mary.
--Yes, I know. We've already known each other. 我们已经互相认识彼此了。（在你的预料情况之前）
Yet=直到现在
用于否定句中：
Is Marco here?
--No, he hasn't arrived yet. 他直到现在还没到。
Does Jill know you're going away?
--No, I haven't told her yet. 我直到现在还没有告诉她。
用于问句中：
Have Jill and Marco arrived yet?
--No yet. We still waiting for them.
Has Crystal started her new job yet?
--No, she will start next week.
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