表示地球椭圆体的形状和大小的重要参数有（）。A.长半轴 B.短半轴 C.扁率及偏心率

读寓言故事，然后回答问题。

Cat: I'm hungry. Hmm... Here comes a mouse. Now I can catch it.

Mouse: Dear cat. Wait a minute. Don't eat me. I can do things for you.

Cat: Oh! What can you do?

Mouse: I can sing.

Cat: Can you dance?

Mouse: No, I can't. But I can climb the tall tree. Then I can catch a bird for you.

Cat: Let me see.

Mouse: Ha Ha! Silly cat! Now I can run away. Bye!

1. Who's hungry?

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2. Can the cat catch the mouse?

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3. The mouse can do things for the cat, really?

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4. Can the mouse dance?

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5. Is the cat silly?

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数轴上到原点距离等于3的点所表示的数是+3[ ]

金属烤瓷冠的基底冠厚度至少为

A．0.1mm
B．0.2mm
C．0.3mm
D．0.5mm
E．1.0mm

管路连接件、附件的配置有哪些要求？