(1) th位于詞首時，可以從詞性上判別其應有的讀音。在名詞、動詞、形容詞和數(shù)詞中th發(fā)清輔音。如：thing, theatre, thunder, thermos, Thursday, theory, theme, throat, thread, think, thank, thrive, thicken, thirteen, thirty, third, thousand, thick, thirsty, thoughtful, thorough 在代詞和一些功能詞中th發(fā)濁輔音.如： them, their, theirs, there, the, than, then, though, thus, therefore, they。只有介詞through是個例外。

(2) th位于詞尾(或音節(jié)之尾)時，其讀音多數(shù)是清輔音，如：bath, breath, tooth, 等。只有在少數(shù)單詞中，如：with, smooth 中讀濁音。

(3) th在詞中并且后面接er時，或者最后一個字母是不發(fā)音的e時，通常也發(fā)濁輔音。例如：feather, weather, whether, leather, further, father, bathe, breathe, southern, northern, either等。在其他情況下發(fā)清輔音。例如：author, faithful, method, nothing, anything, healthy, wealthy。 試讀下列單詞: mother, father, another, brother, health, wealth