a firm command的用法和样例：
- I am articled to a firm of lawyers.
- We must mniatain a firm attitude.
- The old man rocked and cradled Erik in his arms for a moment, and then his eyes opened and set squarely on mine.He said in a firm commanding voice," You take care of this baby.
- Phil was articled to a firm of lawyers.
- He has set up a firm of his own.