单选题:Speaker A: Firstly, allow me to introduce myself. My name is

题目内容:
Speaker A: Firstly, allow me to introduce myself. My name is John Brown, manager of the com-pany.
Speaker B:__________ A.You must be mistaken. I don' t know you at all.
B.Hello, Brown! I haven' t seen you for ages.
C.How do you do, Mr. Brown? Very happy to see you.
D.Hi, John ! Welcome to China.

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答案解析:

设函数ƒ(x)=x2-1,则ƒ(x+2)=(  )

设函数ƒ(x)=x2-1,则ƒ(x+2)=(  ) A.x2+4x+5 B.x2+4x+3 C.x2+2x+ D.x2+2x+3

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经过点B(0,3)且与直线x+2y-3=0垂直的直线方程为(  )

经过点B(0,3)且与直线x+2y-3=0垂直的直线方程为(  ) A.2x-y-3=0 B.y-2x-3=0 C.X+2y-6=0 D.2x+y-3=0

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若3+2i为方程2x2+bx+c=0(b,c∈R)的一个根,则b,c为(  )

若3+2i为方程2x2+bx+c=0(b,c∈R)的一个根,则b,c为(  ) A.b=-12,c=26 B.b=12,c=-26 C.b=26,c=-12 D

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若tana=m且a在第三象限,则cosa的值为(  )

若tana=m且a在第三象限,则cosa的值为(  )

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种群是______的集合体,而群落是种群的集合体。

种群是______的集合体,而群落是种群的集合体。

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