permutation and combination的用法和樣例：
例句
用作名詞 (n.)
- Unique because that particular permutation has not appeared before.
之所以獨一無(wú)二，是因為那種獨特的基因排列組合以前不曾出現過(guò)。 - Besides, the author understood the rule of negative multiplication completely and studied the problem of permutation and combination deeply.
另外，薩瑪瓦爾完全理解了負數的乘法法則，并對排列組合問(wèn)題也有充分的認識。
