Hello everybody ,
I'm Chinese ,an English learner (= and I'm still a Beginner , don't know much about English .
Here ,I'm going to post one problem I meet .
Today ,
When I was watching youtube ,
I heard pronounced Twenty like twen-dy , Seventyfive like seven-ni five .
I don't know if I have heard well .
Hope that someone can give me a solution .
Or give me some suggestions about how to learn English Pronunciation .

Grace

You have just proved what a good ear for languages you have! This is great. Many people cannot even hear what you are hearing. It is correct what you are hearing. It is most probably an American accent. Often the t tends to be softened there. You can here this especially for a t between two vowels, pronounced like a d "universiDy" . But you definitely should not worry when you have such a sharp ear.

Are you talking about listening comprehension or are you talking about pronunciation?

Marianne10 is right. Said quickly, the 't' in words like 'seventy' can either sound like a 'd' (America) or almost disappear (various parts of Britain and Australia).

When you say you want to learn English pronunciation who is it exactly that you want to sound like? An American? An English person? An Australian? An Irish person? They all have different pronunciation, and even different vocabulary and grammar.

Raymondo - Yes you are right. I forgot the gluttal stop in the UK that also swallows the T. That is actually probably trickier to pick up and also the final dark L (model, paddle, etc). I think Grace means listening comprehension. If so it is probably best to use standard material.

In some American accents, you'll also see the t disappear, leaving a pronunciation like "twunny" for 20. Fortunately, almost everyone is going to understand if you pronounce the number 20 "correctly," with the t sound in it.

The other pronunciations occur when people speak quickly, or if they're using informal language -- and it's best not to imitate those speakers until you truly understand the difference in register and situation, much the same way as people shouldn't use slang unless they really understand what the slang terms mean and when they're used.

The best way to understand this is to listen to a wide variety of accents spoken in as many different situations as you can. That way you can compare the similarities and differences.