常用的工具圆锥有（）种。 A.1 B.2 C.3 D.4

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问题单项选择题

常用的工具圆锥有（）种。

A.1

B.2

C.3

D.4

答案

参考答案：B

补全对话，情景问答

1.	— Look at my new _____________. — Oh, how nice!
2.	— What's this? — It's a _____________. It's cold inside.
3.	— Where is your mother, Li Lei? — She's making lunch in the _____________.
4.	— What season is this? — It's _____________.
5.	— Look! Who is he? — Oh! He is a merry man in red clothes. He's _____________.

选择题

(2011年台州调研)如图所示，在匀强磁场中的矩形金属轨道上，有等长的两根金属棒ab和cd，它们以相同的速度匀速运动，则(　　)

A．断开电键K，ab中有感应电流

B．闭合电键K，ab中有感应电流

C．无论断开还是闭合电键K，ab中都有感应电流

D．无论断开还是闭合电键K，ab中都没有感应电流