动词时态（二）：完成时

本节导读

完成时是时态里最让初学者头疼的部分，因为汉语里没有对应的形式。但它在考试里的考法其实很固定：看时间状语（already、yet、for、since、by...），选 have / has done 还是 did，再加上 have been to 与 have gone to 的区别。

学完这一节，你应该能写出现在完成时和过去完成时的结构，能区分现在完成时和一般过去时，会用 for 和 since，并知道哪些动词不能和一段时间连用。

现在完成时

构成和过去分词

现在完成时的结构是 have / has + 过去分词。主语是第三人称单数时用 has，其余用 have。规则动词的过去分词和过去式一样，都是加 ed。不规则动词的过去分词要单独记：

原形	过去式	过去分词
be	was / were	been
do	did	done
go	went	gone
see	saw	seen
take	took	taken
eat	ate	eaten
write	wrote	written
give	gave	given
speak	spoke	spoken
come	came	come
run	ran	run
know	knew	known

两种基本用法

一种是，过去发生的动作对现在产生了影响或结果。常见的信号词有 already、yet、just、ever、never、before、so far：

• I have already finished my homework.（作业已经写完了。）
• Have you finished yet?（你写完了吗？）yet 用在否定句和疑问句的句末。
• Have you ever been to Beijing?（你去过北京吗？）
• I have never seen a panda.（我从来没见过熊猫。）

另一种是，动作或状态从过去开始，一直持续到现在，常和 for、since 连用：

I have lived here for ten years.
我在这里住了十年了。

for 和 since 的区别

for 后面接一段时间，since 后面接一个时间点。提问用 How long：

词	后面接	例子
for	一段时间	for two years, for a week
since	时间点，或一般过去时的从句	since 2015, since last year, since I was a child

have been to、have gone to、have been in

短语	意思	例句
have been to	去过某地（已经回来）	I have been to Hangzhou.
have gone to	去了某地（人不在这里）	He has gone to Hangzhou.
have been in	一直待在某地（可接一段时间）	He has been in Hangzhou for three years.

延续性动词和非延续性动词

buy、die、come、leave、join、begin 这类动作一发生就结束的动词叫非延续性动词，不能直接和一段时间连用。比如不能说 I have bought this bike for two years，要换成延续性的说法：

非延续性动词	要换成	例句
buy	have	I have had this bike for two years.
borrow	keep	I have kept the book for a week.
come, arrive	be here	She has been here since eight.
leave	be away	He has been away for a week.
die	be dead	The old man has been dead for ten years.
join	be a member of	He has been a member of the club for two years.
begin, start	be on	The meeting has been on for an hour.

这条规则只限于肯定句。否定句可以直接用：I haven't seen him for a week.