how to pronounce

[ShirleyLing]

I think I could pronounce "risk" and "last". But I have trouble with "risks" and "lasts". Do I pronounce "risks" as "ris", and "lasts" as "las"?

[English Freak]

That's right, sometimes when you pluralize a noun or put it in the 3rd person singular, it's harder to pronounce. You have to have the sound /s/ at the end, but it's not a must to pronounce it strongly. You just need to pronounce it softly. It's common in spoken English. For sure, they will understand you.

[Raymott]

I think I could pronounce "risk" and "last". But I have trouble with "risks" and "lasts". Do I pronounce "risks" as "ris", and "lasts" as "las"?

You can if that's all you can manage. But you do ris misunderstanding.
Practice hissing 'ssssssssssss' and adding a /k/ or a /t/ in the middle.