【单选题】交换机是一种___________设备.
G.
、若“学生”表中存储了学号、姓名、性别、成绩等字段,则“删除所有女学生记录”的SQL语句是___________。
H.
DELETE * FROM 学生 WHERE 学生.性别=“女”
I.
DELETE FROM 学生 WHERE 学生.性别=女
J.
DELETE FROM 学生 WHERE 学生.性别=“女” K. DELETE * FROM 学生 WHERE 学生.性别=女
【单选题】According to Lynn, what is the specialty at Crab Island?
A.
Genuine farmhouse-style dishes
【单选题】Next morning, the crab disappeared, and my disappointment was bitter at the time. Then I felt happy at last because___.
B.
the crab returned to the sea
C.
I thought perhaps the crab returned to the sea
【单选题】设随机变量X的概率密度为 ,k,a均大于0,且X的数学期望为0.75,则
【单选题】听力原文: The fiddler crab is a living clock. It indicates the time of the day by the color of its skin, which is dark by day and pale by night. The crab's changing skin color follows a regular twenty-fou...
A.
Why they change color.
B.
Whether they change color.
C.
How to use them as clocks.
D.
Where they can be caught.
【简答题】在某一大楼内,电梯的等候时间在[0,5]分钟之间均匀分布,则概率密度函数f(x)=______;等候时间大于0.5分钟的概率为______;电梯在最初45秒钟到达的概率为______;等候时间在1分钟至3分钟之间的概率为______.
【单选题】交换机是一种___________设备.
【简答题】的概率密度 , , 均大于0, 则 ____1(填“大于” “等于”或“小于”).