firm : 指牢固不可动摇或意志、信仰的坚定。
- I'd rather sleep on a firm mattress than a soft one.
- These pears are still too firm to eat.
stable : 多指根基牢固，平衡良好，也指性格或位置等的稳定，不可移动或改变。
- If the foundations of the house aren't stable, collapse is possible.
- After several part-time jobs, he's now got a stable job in a bank.
- The hospital said she was in a stable condition (= not likely to get worse) following the operation.
steady : 指保持平衡不动摇。用于有形物时，指没有根基的稳固，也指动中的稳。
- I'll hold the boat steady while you climb in.
- Most rental prices have held steady this year.
- Young people assume that if you are in a steady relationship, you don't have to worry about HIV.
- The procession moved through the streets at a steady pace.
- Orders for new ships are rising, after several years of steady decline.
- Over the last ten years he has produced a steady flow/stream/trickle of articles and papers.
- Progress has been slow but steady.