Yes, you are right, you do need to pronounce the "th" sound. It is "th" as in "the" and "this", not "three" and "thirsty". hope that helps :-)

Both are correct: "cloTHes" with the "th" sound or pronounced like "close." http://www.merriam-webster.com/dictionary/clothes You can hear the pronunciation of almost any English word at merriam-webster.com. It is one of the best and most reliable dictionary sites on the Internet.

The following site has a person say aloud the words or sentence that you have typed in. Choose the accent that you like after you type in your word/sentence. http://www.oddcast.com/home/demos/tts/tts_example.php?sitepal

(if you can read pronunciation symbols) US pronusciation = [kloʊðz;kloʊz] Britaion pronunciation = [kləʊðz;kləʊz] hope it helps!

And the word "sixth", we can simply pronounce "sikst"?