gradually; by degrees; steps; stairs; staircase; terrace; notches; serration; indentation; jaggies; notched; serrated; jagged; corrugated; milled; gradually; by degrees; little by little; more and more; increasingly
段段
notches; serration; indentation; jaggies; notched; serrated; jagged; corrugated; milled; gradually; by degrees; little by little; more and more; increasingly; steps; stairs; staircase; terrace
