Non-gradable adjectives cannot have different degrees of intensity because they are extreme or already maximum intensity. For example boiling means very hot so we cannot say very boiling! However, we can use some modifiers for emphasis!
Examples of non-gradable (extreme adjectives) are freezing, furious, hilarious, awful, terrified, starving, tiny and exhausted.
I’m starving! → This means I’m very hungry so I can’t say I’m very starving!
I’m absolutely starving! → This means I could eat a horse! It’s emphatic!
The modifiers we can use with non-gradable adjectives are:
*When we use quite with extreme adjectives it means absolutely:
The film was quite terrifying.
You can review modifiers with non-gradable (extreme) adjectives in C1.1 Unit 1