consonant /t/ contrasts with consonant /d/

[playagain]

Please help me about my reporting in my English Class...
I was asked to report about consonant /t/ contrasts with consonant /d/ (consonant contrast /d/ and /t/)...
My problem is that I have no idea about this topic..
Please do help me... I need to report this in front of the class next week.. Please give me some ideas or some links(websites) for me to study...

Thanks in advance...
Any help will be much appreciated
-playagain

 

[Hi_there_Carl]

Maybe this will help: Flap consonant - Wikipedia, the free encyclopedia ;-)

 

[playagain]

but how flap consonants related to my topic? where is the contrast of /t/ with consonant /d/???