reduced和reduce

reduce的意思是：减少、降低，是vi/vt
它的过去式和过去分词都是reduced，
但是reduced的意思是减少的，是形容词这是为什么呢？

分词（包括过去分词和现在分词）可以做形容词，没什么奇怪。 起形容词作用的分词（形容词型分词）

a. 分词作定语的用法
1)总的特点
分词可以作定语，修饰或是限制一个名词，可以放在它前面，也可以放在它后面。一般说来，简单分词可以放在名词前面，分词短语放在名词后面。
a)放在名词前面的分词
1/表示动作的分词：
一个现在分词或过去分词放在名词前时，可以表示一时的动作，这时它的动词特点胜过形容词特点，相当于一个定语从句
Do you see the rising sun(=sun which is rising) in the east?
They tried to surround the retreating troops (=troops which were retreating).
The roaring lion frightened all the animals in the jungle.
They tried to deliver the besieged city (=city which was being besieged).
These repeated efforts(=efforts which were being repeated) were still inadequate.
Those oppressed nations (=nations that are being oppressed ) are rising to liberate themselves.
2/表示特点的分词：
它也可以表示比较长久或永久性的特点。这时它的形容词特点胜过它的动词特点：
Germs are living creatures (=not inanimate things, creatures that can live).
She is a charming lady (attractive lady, lady who charms others)
The working classes are usually poor.
There were many flying fish.
We watched the moving pictures (=motion pictures)
Used cars (=old cars,cars which have been used) are cheaper than new ones/
Stolen love (=Secret love, love which is stolen), though dangerous, tastes exceptionally sweet.
This printed matter may be sent by mail.
3/和用作形容词的动名词的差别：
用在名词前的现在分词和用在名词前起形容词作用的动名词是有区别的，从意思上、重音上及是否加连字号，都有区别。下面各对句子中，第一句中带-ing词尾的动词为分词，第二句中带-ing词尾的动词为动名词：
Boiling water(=Water that is boiling) can produce enormous power.
Water begins to boil at the boiling-point(=point at which liquid boils;而不是point which boils).
He is a walking dictionary (=dictionary that canwalk, learned man).
He came with a walking-stick (=stick for walking;非stick that os walking)
How clever that dancing bear (=bear that is dancing) is!
He is a dancing-master (=master who teaches dancing).
someone said many years ago that China was a sleeping lion (=lion that was sleeping).
He is in the sleeping-car (=car for sleeping,而不是 car that is sleeping).
Running water is cleaner than stagnant water.
It is a running-track for sportsmen.
4/用作名词的情况
和形容词一样，某些分词在加the时（后面不跟名词），可以代表一类人或一种抽象东西：
Which are more numerous, the dead or the living (=the living people)
Something must be done immediately with the wounded and the dying.
What should we do with the oppressed, the defeated the insulted and the injured?
Can we say anything about the unseen (=the thing unseen) and the unknown (=the thing unknown)?
放在名词后的分词
放在名词后的分词多数是分词短语，它可以变成一个定语从句（尽管定语从句不一定都能变成分词短语）：
1/表示一时动作的分词短语：
The danger threatening the world (=which is threatening the area ) is too many people with too little food.
They looked on at the city being attacked by the enemy (=which was being attacked by the enemy).
The man being followed by guards (=who are being followed by guards) is a party leader.
2/表示长久特点的分词短语：
A man respecting others (=who respects others ) will be respected.
Can you teach a boy refusing to be taught (=who refuses to be taught)?
It is difficult to save a man enchanted by the beauty of a woman.
Books called the comics (=that are called the comics ) are sometimes harmful to children.
Any books well read (=that are well read ) are good books and any men well treated are good men.

它的过去式和过去分词都是reduced，
但是reduced的意思是减少的，是形容词    这是为什么呢？

回答：动词的过去分词可以充当形容，词性变为形容词性了。可以充当定语，后置定语

因为一直用sth.be.reduced 所以就理解为形容词了