The key to choosing which one is to look at the comparison object.

(1) Strong

Mainly used to compare strengths and weaknesses, this is obviously not appropriate.

(2) hardness; (3) firmness; (4) Robustness depends only on the robustness of the object, but on the comparison object. Often expressed in different Chinese characters.

② hardness

Used for general soft and hard.

(3) Strong

Emphasize the hardness a little. Can be used for intangible comparison.

Example: strong will (strong will)

④ Fixation

Personal understanding is a bit conservative. It is equivalent to when Chinese emphasizes firmness a little. Can be used for intangible comparison.

For example, ammunition, ammunition.

Keep your word, keep your word!

ご means まで.