在Visual Fox Pro中变量分为两类,分别是______。
A.全局变量和局部变量
B.简单变量和数组变量
C.内存变量和字段变量
D.字符变量和数值变量
A.全局变量和局部变量
B.简单变量和数组变量
C.内存变量和字段变量
D.字符变量和数值变量
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
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
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
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