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【单选题】
What can be inferred from paragraph 1?A．Coral first evolved more than 500,000 years ago.##A.
What can be inferred from paragraph 1? A．Coral first evolved more than 500,000 years ago.
B.
Scientists are only interested in things both ancient and large.
C.
Coral is a type of colorful rock that attracts fish.
D.
No type of coral ever builds a colony more than a meter hig
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【简答题】Fill in each blank with one suitable word from the list below, Each word in the list can be used once only. a actually bite catch caught dearest deep deeply dice distre evidence. ...
【简答题】Fill in each blank with one suitable word from the list below, Each word in the list can be used once only. a actually bite catch caught dearest deep deeply dice distre evidence. ...
【简答题】设x，y，z∈R且x+2y+3z=1 （I）当z=1，|x+y|+|y+1|＞2时，求x的取值范围； （II）当x＞0，y＞0，z＞0时，求 u= x 2 x+1 + 2 y 2 y+2 + 3 z 2 z+3 的最小值．
【简答题】设函数u 1 =u 1 (x，y，z)与u 2 =u 2 (x，y，z)均满足拉普拉斯方程△u=0．试证明函数v=u 1 (x，y，z)+(x 2 +y 2 +z 2 )u 2 (x，y，z)满足方程△(△v)=0．
【简答题】设x，y，z，w为四个互不相等的实数，并且x+ 1 y =y+ 1 z =z+ 1 ω =w+ 1 x 求证：x 2 y 2 z 2 w 2 =1
【简答题】设集合X={x 1 ,x 2 ,x 3 },Y={y 1 ,y 2 },Z={z 1 ,z 2 }，求X×Y×Z．
【单选题】1 New technology often creates unanticipated problems. 2 Automobiles, for ex- ample, provide numerous benefits, but they also pollute the air and kill about fifty thousand Americans each year. 3 It is...
A.
1
B.
2
C.
3
D.
4
E.
5
【单选题】在复平面内，设向量 p 1 =( x 1 ， y 1 )， p 2 =( x 2 ， y 2 )又设复数 z 1 = x 1 + y 1 i； z 2 = x 2 + y 2 i（x 1 ，x 2 ，y 1 ，y 2 ∈R），则 p 1 ? p 2 等于（ ）
A.
. z 1 z 2 + z 1 . z 2
B.
. z 1 z 2 - z 1 . z 2
C.
1 2 （ . z 1 z 2 - z 1 . z 2 ）
D.
1 2 （ . z 1 z 2 + z 1 . z 2 ）
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