辅音字符th有清与浊两种读音：

　　1当位于词首时,可以从词性上判别其应有的读音.请看：

　　第一类：在以下4种词类th读清音,即国际音标的θ：

　　a.Noun名词：thing,theatre,thumb大拇指,thunder雷,

　　thermos热水瓶,Thursday,theory,theme,throat喉咙,thread线

　　b.Verb动词：think,thank,throw,thrive,thicken,

　　c.Numeral数词：three,thirteen,thirty,third,thousand

　　d.Adjective形容词：thin,thick,thirsty,thoughtful,

　　thorough彻底的

　　第二类：在以下两种词类th读浊音：

　　a.Pronoun代词：they,them,their,theirs,this,these,

　　that,those,there,thy[旧时用法]你的

　　b.Functionalterms功能词：the,than,then,though,thus,

　　therefore

　　2当位于词尾（或音节之尾）时,其读音多数是清音,如：bath,breath,both,cloth,tooth,health,wealth,arithmetic等.只有在少数单词中,如：with,smooth中读浊音.

　　3当位于两个元音之间时,其读音多数是浊音.如：other,mother,brother,another,father,weather,feather,leather,further,breathe.

　　但是,也有读清音的.如在单词method,nothing,anything,sympathy,sympathetic,mathematics,healthy,wealthy,Luther,Marathon(马拉松)等.