题目内容
选择题
本大题共12小题，每小题2分。在每小题所给出的四个选项中，只有一项是符合题目要求的。
心理学研究应以正常健康人为对象，人的本性是善良的并蕴藏着巨大的潜能。持这种观点的心理学理论流派是
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已知ABC公司加权平均的最低投资利润率为20%，其下设的甲投资中心资额为200万元，剩余收益为20万元，则该中心的投资利润率为()。
A．The Grand Theatre.B．The Modern Theatre.C．The Grand Zoo.D．The Grand Ice Centre.
听力原文： When men first lived on the earth a long time ago, they had no proper place to live in. In order to get away from the heat of the sun, to keep themselves warm and dry, they found caves. Caves really gave them some kind of help. Some of these early men built their shelters up in the tree to escape wild animals. They had a hard life and had to go about from place to place for food. Much later on, their lives began to change. They learnt how to keep animals in herds. As they had to move their herds of animals from place to place for grassland, they had to build shelters which were easily carried about.
When they finally learnt the art of farming, they had to clean forests and started planting crops. After that, they had to think about building more permanent shelters. Old houses were built at first with wood and they even use grass as roofs. This went on for a long time. They kept making their houses better. Today, houses of all kinds are built. They are strong, permanent and can last a very long time.
(30)
给定关系模式R(U，F)，U＝{A，B，C，D，E，F}，F＝{B→F，D→A，A→E， AE→B}，那么属性A的闭包为(62)，R的候选关键字为(63)。
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