th：
(1)th位於詞首時,可以從詞性上判別其應有的讀音.在名詞、動詞、形容詞和數詞中th發清子音.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發濁子音.如：them,their,theirs,there,the,than,then,though,thus,therefore,they.只有介詞through是個例外.
(2)th位於詞尾（或音節之尾）時,其讀音多數是清子音,如：bath,breath,tooth,等.只有在少數單詞中,如：with,smooth中讀濁音.
(3)th在詞中並且後面接er時,或者最後一個字母是不發音的e時,通常也發濁子音.例如：feather,weather,whether,leather,further,father,bathe,breathe,southern,northern,either等.在其他情況下發清子音.例如：author,faithful,method,nothing,anything,healthy,wealthy.
tch：發/t?/的音。就是中文“吃”[chi]裡面的[ch]
th：
(1)th位於詞首時,可以從詞性上判別其應有的讀音.在名詞、動詞、形容詞和數詞中th發清子音.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發濁子音.如：them,their,theirs,there,the,than,then,though,thus,therefore,they.只有介詞through是個例外.
(2)th位於詞尾（或音節之尾）時,其讀音多數是清子音,如：bath,breath,tooth,等.只有在少數單詞中,如：with,smooth中讀濁音.
(3)th在詞中並且後面接er時,或者最後一個字母是不發音的e時,通常也發濁子音.例如：feather,weather,whether,leather,further,father,bathe,breathe,southern,northern,either等.在其他情況下發清子音.例如：author,faithful,method,nothing,anything,healthy,wealthy.
tch：發/t?/的音。就是中文“吃”[chi]裡面的[ch]