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问题 选择题

抛物线y2=4x关于直线x＋y=0对称的抛物线的方程是（   ）

A．x2＝4y

B．y2=－4x

C．y=－4x2

D．x2=－4y

答案

答案：D

（x，y）关于x＋y=0的对称点（－y，－x）在抛物线y2=4x。

名词解释

协奏曲（Concerto）
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单项选择题

When a survival craft drill is held，the person in charge must insure that（）.

A.all survival craft are lowered to the water，launched，and operated for thirty minutes

B.all davits used for launching liferafts are operated

C.each emergency position indicating radio beacon is tested for thirty minutes

D.the helicopter pad landing lights are operating in a quick-flashing mode
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