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问题
选择题
What does your mother do?[ ]
A. She is a teacher.
B. I am a teacher.
C. He is teacher.
答案
答案:
A
解答题
先化简,再求值:2(3
m
2
-mn-
1
2
n
2
)-
1
2
(
m
2
-2mn-4
n
2
)
,其中m=-2,n=
1
2
.
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