2.古之善用兵者，能使敌人前后不相及，众寡不相恃，贵贱不相救，上下不相收，卒离而不集，兵合而不齐。

　　合于利而动，不合于利而止。

　　敢问:“敌众整而将来，待之若何？”

　　曰：“先夺其所爱，则听矣。”

　　兵之情主速，乘人之不及,由不虞之道，攻其所不戒也。

　　这句啥意思：

　　从前善于指挥作战的人，能使敌人前后部队不能相互策应，主力和小部队无法相互依靠，

　　官兵之间不能相互救援，上下级之间不能互相联络，士兵分散不能集中，合兵布阵也不整齐。

　　对我有利就打，对我无利就停止行动。

　　试问：敌人兵员众多且又阵势严整向我发起进攻，那该用什么办法对付它呢？

　　回答是：先夺取敌人最关心爱护的，这样就听从我们的摆布了。

　　用兵之理贵在神速，要乘敌人措手不及的时机，走敌人意料不到的道路，攻击敌人没有戒备的地方。

　　英文这么说：

　　Those who were called skillful leaders of old knew how to drive a wedge between the enemy's front and rearto prevent co-operation between his large and small divisions;to hinder the good troops from rescuing the bad,the officers from rallying their men.When the enemy's men were united, they managed to keep them in disorder.When it was to their advantage, they made a forward move; when otherwise, they stopped still.If asked how to cope with a great host of the enemy in orderly array and on the point of marching to the attack,I should say: "Begin by seizing something which your opponent holds dear; then he will be amenable to yourwill."Rapidity is the essence of war: take advantage of the enemy's unreadiness, make your way by unexpected routes,and attack unguarded spots.

　　单句理解

　　所谓古之善用兵者，能使敌人前后不相及，众寡不相恃，贵贱不相救，上下不相收，卒离而不集，兵合而不齐。合于利而动，不合于利而止。孙子在这里提出了“和余力而动，不合于利而止”的战争指导原则。这种原则主要是使敌人前后不能相救，上下不能相及，从而阻断敌人内部的有机联系，达到降级敌人战斗力的目的。总之，军事行动要以对我方有利为原则。