Big problem with [θ] [ð] and [s,z] sounds

[Russian learner]

Hi. I've got a big problem with pronunciation [θ] and [ð] and [s,z] sounds, when they're close. I don't know how to explain that, but just look at these sentences:
1. Is this pencil?
2. Cross the road.
3. These sentences.

How to pronounce them? I tried, but broke tongue.
My pronunciation is about:
1.[ iðis pensil]?
2.[croθe road]
3.[ðis`entences]

 

[GoesStation]

Number 1 needs an article: Is this a/the pencil?

I'm afraid you have to pronounce the /z/ in "is", the /s/ in "cross", and both sibilants in "these sentences". For sentence 1, I stop the flow of air momentarily between is and this while moving my tongue forward and arching it to touch the back of my upper front teeth. Perhaps you can practice is ... this, starting with a long pause between the words and gradually shortening it.

The same strategy might help with sentences 2 and 3.

 

[Donna Norton]

Here is a great video https://www.youtube.com/watch?v=3LD7m3luv0Y to see how should your mouth move when pronouncing these sounds. Just make sure to practice a lot! Almost all foreigners have problems with pronouncing these sounds, specially "th" sound. Also here https://custom-writing.org/blog/phonetics you can find excellent practice advice on how to improve your pronounciation.

 

[probus]

"Non-native-speakers (of English)" is more correct and precise than "foreigners".