Precise.
In what context: harder as in metals, or harder as in difficult?
The opposite of "easier" is "harder."
always get harder
Hard
Try harder can be the other way to replace work harder, too.
in what context it is harder than stone = katai its harder homework = moto musukashii
Sometimes; It depends on the context. When you use the word "harder" as for difficulty level, then yes, tougher is a synonym for harder. If you are talking about the firmness of an object, tougher is NOT a synonym for harder. Or if you're talking about the chewyness of something.
Im gonna guess and say occur.
I will accurate you!
The harder a word is, the harder it is to spell the word. The online website, Spell Zone, gives tips on how to learn to spell even the hardest words.
The correct form is "harder." When comparing two things, the comparative form of "hard" is "harder." Adding "more" before "hard" would be redundant and incorrect. So, it is grammatically accurate to say "harder" when comparing the difficulty of two things.
Your assertions are not accurate.