物理兴趣小组用遥控汽车做了如下实验：在小车上固定一块长木板，然后把遥控汽车放到木板的一端（如图）.控制遥控汽车向左运动时，小车同时向右运动.该现象说明物体间力的作用是____的.判断遥控汽车对木板产生了作用力的依据是____；

   Mrs. Black lives on Second Avenue. New Year is coming. She wants to send (寄) a card to her friend in Toronto, but she doesn’t know where the post office is. She asks her neighbor (邻居) Mary, “ Is there a post office near here? I want to send a card.”
   “The post office is not near from here,” answers Mary, “but you don’t need to go to the post office to post the card. There is a mailboxin front of the supermarket. You can put your card into the mailbox”

如图所示，当歼﹣15舰载机起飞离开“辽宁舰”后，“辽宁舰”所受到的浮力将____ ，以舰载机为参照物“辽宁舰”是____的．

《世界文明史》介绍：罗马成文法的组成部分之一“是罗马城市行政官在执法过程中所做的决定……行政官……可以根据每一个别案例的情况做出裁量，而不必僵硬地按照有关法律条文的字面含义进行判决。他的这种决定成为事实上的判例法。”由此可见，罗马法的显著特点是（ ）