大明宣德年制铜香炉价格:英语语法问题

都用现在完成时
后面两个还可以用想在完成进行时
结构为have/has been doing

现在完成时

现在完成时是英语时态中最不好掌握的时态，因为对我们来说，它很难在汉语中找到相对应的说法，下面从几个方面分析一下现在完成时的用法。
1． 现在完成时的定义：

2． 强调过去的动作和状态对现在产生的影响和结果。
常用的时间状语有：already, yet, never，有时没有时间状语；多是一般疑问句。

I have already seen the film.
Have you decided yet?

3． 刚刚和最近发生的动作和状态。
常用的时间状语有：just, lately, recently, in the past few days/weeks
注意：just 和just now用不同的时态，just now(刚才)一般用过去时。

I have just phoned him?
I have visited my parents recently.

4． 从过去一直延续到现在的动作和状态。
常用的时间状语有：since, （可用作介词和连词）for
注意：主句的谓语动词一般是延续性的动词，如果是否定形式，主句的谓语动词可用瞬间动词，否则，不能用瞬间动词。

I have lived here for 20 years.
I have lived here since I came to this city
I have learned English since 10 years ago.
He hasn't come to visit us for a few months.

5． 从过去到现在一段时间的动作和状态。
常用的时间状语有：up till now, so far, in this morning, in this week, in this year, in my life
注意：这两句话的区别
I have seen him this morning. (时间还在上午)
I saw him this morning. (时间不是在上午了)

We have learned so many things from you so far.
I have seen any bird like this in my life.

6． 对过去的体验和经历。
常用的时间状语有：before, ever, once, twice, many times
注意：这两句话的区别
I have been to Beijing （去过北京）
I have gone to Beijing（去北京了，人还没回来〕

Have you seen tiger before?
I have been to Shanghai many times.

从上面几方面的分析， 我们把现在完成的用法和时间状语联系起来一起考虑，掌握完成时态的用法。