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搜题
【多选题】
数据预处理方法主要有( )。A.
数据清洗
B.
数据集成
C.
数据变换
D.
数据归约
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皮皮学刷刷变学霸
举一反三
【简答题】已知x为实数，且x 2 + 1 x 2 =3，则x 3 + 1 x 3 的值是______．
【单选题】已知函数f（x）=x- x -1，g（x）=x+2 x ，h（x）=x+lnx，零点分别为x 1 ，x 2 ，x 3 ，则（ ）
A.
x 1 ＜x 2 ＜x 3
B.
x 2 ＜x 1 ＜x 3
C.
x 3 ＜x 1 ＜x 2
D.
x 2 ＜x 3 ＜x 1
【单选题】已知x 1 ，x 2 是方程x 2 +3x=4的两根，则（ ）
A.
x 1 +x 2 =-3，x 1 ?x 2 =-4
B.
x 1 +x 2 =3，x 1 ?x 2 =4
C.
x 1 +x 2 =-3，x 1 ?x 2 =4
D.
x 1 +x 2 =3，x 1 ?x 2 =-4
【单选题】已知函数f（x）=x+2 x ，g（x）=x+lnx， 的零点分别为x 1 ，x 2 ，x 3 ，则x 1 ，x 2 ，x 3 的大小关系是 [ ]
A.
x 1 ＜x 2 ＜x 3
B.
x 2 ＜x 1 ＜x 3
C.
x 1 ＜x 3 ＜x 2
D.
x 3 ＜x 2 ＜x 1
【单选题】已知函数f（x）=x+2 x ，g（x）=x+lnx，h（x）=x 3 +x-2的零点分别为x 1 ，x 2 ，x 3 ，则（ ）
A.
x 3 ＜x 1 ＜x 2
B.
x 1 ＜x 3 ＜x 2
C.
x 2 ＜x 3 ＜x 1
D.
x 1 ＜x 2 ＜x 3
【单选题】According to the passage, false beards were worn by those who considered themselves to be ______.
A.
handsome and mature
B.
too young to have beards
C.
aristocrats or fashionable dandies
D.
royalty
【单选题】In former times doctors in Taiwan, who were considered saviors, were greatly admired. This is not only because they were able to relieve sick people of their pain and save their lives, but because the...
A.
Because they were a group of qualified doctors
B.
Because they ranked first in wealth
C.
Because they were able to cure the sick of poverty
D.
Because they were the doctors with medical morals as well as medical skill
【单选题】In England, people who used forks were considered ______ before the custom became popular.
A.
well mannered
B.
show-offs and sissies
C.
overnice
D.
both B and C
【简答题】已知：x 1 、x 2 是方程x 2 +4x-3=0的两根，则 1 x 1 + 1 x 2 =______．
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