(1) th位于詞首時(shí),可以從詞性上判別其應(yīng)有的讀音.在名詞、動(dòng)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(gè)例外.
(2) th位于詞尾（或音節(jié)之尾）時(shí),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(shí),或者最后一個(gè)字母是不發(fā)音的e時(shí),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