在Visual Fox Pro中变量分为两类，分别是______。

A.趋近型、抑制型

B.内倾型、外倾型

C.活动型、情绪型、社交型、冲动型

D.容易型、困难型、慢热型、交叉型

A.直线回归分析的两相关变量可区分为自变量和依变量

B.直线相关分析研究的变量呈平行关系

C.两相关变量间的决定系数等于其相关系数的平方

D.相关系数可用回归系数表示，反之则不然

A.对同一组数据来说，回归系数和相关系数的假设检验是不等价的

B.直线回归分析的两相关变量可区分为自变量和依变量

C.两相关变量间的决定系数等于其相关系数的平方

D.相关系数可用回归系数表示，反之则不然

E.相关变量x与y的直线回归分析中，回归系数显著表明x与y一定呈直线关系

A.ERROR

B.DESTROY

C.INIT

D.DELETE

The film was picked up by a branch of 20th Century Fox and will be in a few cities this fall.

A．freed

B．opened

C．started

D．released

A.事件

B.工具

C.控件

D.窗体

素都有明显效应。相似的捕食者—猎物循环中所涉及的相邻种群经常发生同步振荡，David Vasseur 和Jeremy Fox利用理论及实验室缩微环境发现，当捕食者存在时，猎物种群之间的扩散是造成这种相位锁定（相位同步）的原因。扩散是不同生物（Vasseur和Fox所研究的动物是雪兔和加拿大猞猁）从一个分离的种群向另一个转移的能力。由这项工作所获得的模型对于代表捕食者—猎物和宿主—病原体系统的参数的大范围变化都是可靠的，说明它可能具有普遍适用性。

给本段文字选择一个恰当的标题（）。

A.生态系统中的同步波动

B. 种群扩散的意义

C. 种群同步波动探秘

D. 生态系统新发现

d that feeds on fruit instead of insects. Like all bats, flying foxes hang themselves by their toes when it rest, and travel in great crowds when out flying. A group will live in one spot for years. Sometimes several hundreds of them occupy (占据) a single tree. As they return to the tree toward sunrise, they quarrel among themselves and fight for the best places until long after daylight.

Flying foxes have babies once a year, giving birth to only one at a time. At first the mother has to carry the baby on her breast wherever she goes. Later she leaves it hanging up, and brings back food for it to eat. Sometimes a baby falls down to the ground and squeaks(尖叫) for help. Then the older ones swoop (俯冲) down and try to pick it up. If they fail to do so, it will die, Often hundreds of dead baby bats can be found lying on the ground at the foot of a tree.

The passage tells us that there is no difference between, the flying fox and the ordinary hat in ______. ()

A．their size

B．their appearance

C．the way they rest

D．the kind of food they eat

A.#99

B.#19

C.#29

D.#39