形容词转化为动词：
The city quieted down again.
We must lower our expenses.
Don’t dirty your new dress.
He pretends to busy himself writing.
少数其他词类也可用做动词：
Truth will out.
This will help to further the sciences.
有些形容词可以转化为名词
The temperature reached a new high.
I enjoy the quiet of the country.
This was a custom among the ancients.
They kept indoors in the dead of winter.
有些形容词可以转化为副词：
He sells his goods very dear.
The blow struck him full in the face.
Come closer so that I can see you.
You can live cheaper in the smaller towns.
一些其他转化情况：
He walked north. 名→副
I’ll drive you home. 名→副
The future is full of ifs. 连→名
She was a very forward young lady. 副→形
They asked him to give a repeat performance. 动→形
She paled when we told her the news. 形→动
Don’t ask the whys. 连→名
During the war we had to black out all our windows. 形→动
派生法
派生法又叫词缀法，即在一个单词前或其后加上词缀，构成新的单词。中学英语中以派生法生成的词汇占整个中学词汇总量的25％。一般说来前缀不会改变一个词的词性，后缀往往改变词性。
否定前缀:
表示否定意义的前缀常用的有dis-, il-, im-, in-, ir-, mis-, non-, un-等，在单词的前面加这类前缀常构成与该词意义相反的新词。
un +形容词：unfit, unhappy, unfair, unlucky, unfortunate, unkind, unimportant, unnecessary, uncomfortable, unselfish, unusual, uncommon, unexpected, unknown, unthinkable, unbelievable, unseen, unforgettable, unwise, unhealthy, unpleasant, unable, untrue
由un＋形容词构成的词除了unknown, unseen, unfit等词之外，其它词都可变为加-ly的副词（个别形容词尾需要变动）。
un+副词：undoubtedly, unexpectedly, unfortunately, unusually, unhappily, unluckily
un＋动词：uncover, untie, unlock, undress, undo, unpack
im＋形容词：impossible, impolite
in＋形容词：incorrect, incomplete, invisible, independent
ir＋形容词：irregular
mis＋动词：misspell, misunderstand, mistake
dis＋名词：dishonour, disease, discomfort
dis＋形容词：dishonest, discouraged
dis＋动词：disappear, dislike, discover, disclose, disagree, discomfort, dismiss
表示其他意义的前缀：
常用的有a-（多构成表语形容词）, anti- （反对；抵抗）, auto- （自动）, co- （共同）, en- （使）,inter- （互相）, re- （再；又）, sub- （下面的；次；小）, tele- （强调距离）等。
a-，大多加在音节较少的名词或不及物动词上构成新词，表示“在……之上、向……、处于……状态”：
ahead, abroad, aside, alive, awake, above, about等。
fore-，表示“在……前面”：forehead, foreground, forearm, foreleg
in, il, im, ir表示“向……内，在……内”：inside, include, import
inter-，表示“在……间、相互”：international
intro-，表示“在（向）……内”：introduce
out-，表示“向外”：outside, outlook, outdoors, outflow
over-，表示“在上面的、在外的”：overhead, overlook, overcoat, overcome, overtime, overgrow
pre-，表示“在前”：prefix, preposition
pro-，表示“在（向）前”：progress, programme
sur-，表示“在……上”：surface, surround
trans-，表示“转移”：translate
under-，表示“在……下”：underground, underline