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【单选题】
In the OSI model of network architecture not based on specific model, operating system or company proposed by ISO, layer 2 and layer 4 are respectively ().A.
physical layer and network layer
B.
data link layer and transmission layer
C.
Network layer and presentation layer
D.
session layer and application layer
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举一反三
【单选题】A commonly used rule of thumb is that it costs approximately ____ times as much to get a new customer as it does to keep an existing customer.
A.
three
B.
four
C.
five
D.
six
【单选题】修改表字段的数据类型的基本语句是【】
A.
ALTER TABLE 表名 MODIFY 数据类型 字段名
B.
ALTER TABLE 表名 MODIFY 字段名 数据类型
C.
ALTER TABLE 表名 CHANGE 字段名 数据类型
D.
ALTER TABLE 表名 CHANGE 数据类型 字段名
【单选题】I like this 5G cellphone very much, but it costs almost _______that one.
A.
four times as many as
B.
as four times many as
C.
four times as much as
D.
as four times much as
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