一、在形容词词尾直接加-ly.
如:real-really; helpful-helpfully; careful-carefully; hopeful-hopefully; slow-slowly; quick-quickly; quiet-quietly
二、以辅音字母加y结尾的形容词要变y为i,然后再加-ly.
如:busy-busily; angry-angrily; easy-easily
三、某些以辅音字母加不发音的字母e结尾和以-ue结尾的形容词要先去掉e,然后再加-y或-ly.如:terrible-terribly; true-truly; gentle-gently
另外,副词还可以由形容词加前缀a-得来,如:loud (adj.)-aloud (adv.)
此外,部分名词加后缀也可变成副词,如:part-partly.
例句:It is partly her fault.有部分是她的错.
需注意:friendly; motherly; lovely等词是形容词而非副词.