The pronunciations between "th" and "s"

[Danielbegood]

I don't know how to pronounce the words with "th" or "s" reasonably.

I mean there's no difference when I say SINK & THINK, SING & THING, etc. Any suggestions?

[5jj]

Welcome to the forum, Danielbegood.

/s/ is pronounced with the tongue very close to the hard ridge behind the top front teeth. For /ð / and /θ/ (the 'th' sounds), move your tongue forward until it's touching the front teeth. Indeed, a tiny part of the tongue can press through between the top and bottom front teeth.

[BobK]

So look in a mirror. With /s/ and /z/ you can't see the tip of the tongue.

b

[Danielbegood]

Thanks a lot!