3．Apes and humans beings share a lot in common when it comes to behavior．The evidence taken from the observation of the behavior of apes and children suggests that there are three causes for the outbreak of fighting and the exhibition of （51）D by individuals．
One of the most common causes of fighting among both children and apes was over the （52）B of external objects．The argument over the ownership of any desired object---food，clothes，toys，females，and the affection of others---was sufficient reason to （53）A force．In a case of monkeys'disagreement over females．thirty females were killed．Two points are of particular interest to notice about these fights for possession．
In the first place，the fights are often carried to such an extreme that they end in the （54）C destruction of the objects of common desire．Toys are torn to pieces and females are killed．
In the second place it is observable，that （55）A occurs when an object is desired by only one person or by someone else．There were many cases where toys and other objects which had been thrown away as useless were （56）B defended by their owners when they became the object of some other child's desire．
Another cause of aggression is the tendency for children and apes are greatly to （57）D the invading of a stranger into their group．A new child in the class may be laughed at，isolated，and disliked．A new monkey may be bitten to death．It is interesting to note that anger occurs when a stranger comes from the （58）A species．Monkeys do not mind being （59）C by a goat or a rat．Children do not object when animals are introduced to the group．As a matter of fact，such newcomers are often （60）D．But when monkeys meet a new monkey or children a strange child，aggression often occurs．This strongly suggests that the reason for the aggression is fundamentally possessiveness．The（61）C of the newcomers is feared．The present members of the group feel that there will be more competitors for the food or the attention of the adults．
Finally，another common source of fighting among children is a frustration or failure in their own （62）B．A child will be stopped either by （63）A causes such as bad weather or illness from doing something he wishes to do，for example，sail his boat or ride the bicycle．Sometimes the activity may be （64）D because of the opposition of some adult．The child may also frustrate itself by （65）B，through lack of skill or strength，to complete successfully some desired activity．Such a child will then in the ordinary sense become"naughty"．He will be in a bad or unfriendly temper．
| 51．A．fulfillment | B．excitement | C．isolation | D．aggressiveness |
| 52．A．usage | B．possession | C．value | D．collection |
| 53．A．turn to | B．drive away | C．come over | D．make into |
| 54．A．moderate | B．subtle | C．complete | D．temporary |
| 55．A．conflict | B．negotiation | C．agreement | D．donation |
| 56．A．reluctantly | B．violently | C．unwillingly | D．peacefully |
| 57．A．ignore | B．accept | C．prove | D．hate |
| 58．A．similar | B．modest | C．strong | D．reliable |
| 59．A．observed | B．protected | C．joined | D．spoiled |
| 60．A．offensive | B．considerate | C．generous | D．welcomed |
| 61．A．strength | B．attitude | C．competition | D．emotion |
| 62．A．knowledge | B．activity | C．study | D．personality |
| 63．A．natural | B．physical | C．financial | D．academic |
| 64．A．enhanced | B．operated | C．extended | D．prevented |
| 65．A．learning | B．failing | C．imitating | D．refusing． |
