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问题 选择题

已知椭圆的焦点是F1、F2，P是椭圆上的一个动点，如果延长F1P到Q，使得|PQ|=|PF2|，那么动点Q的轨迹是[ ]

A．圆

B．椭圆

C．双曲线的一支

D．抛物线

答案

答案：A

单项选择题

Cross-sectional returns studies contend that:（）

A. all securities should have equal risk-adjusted returns because security prices should reflect all public information that would influence the security’s risk.

B. all securities should have equal risk-adjusted returns because security prices should not reflect all public information that would influence the security’s risk.

C. securities should not have equal risk-adjusted returns because security prices should not reflect all public information that would influence the security’s risk.
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多项选择题

周期性健康检查的优点（）。

A.在具体时间内了解危险因素

B.对无症状人群进行早发现、早治疗

C.对高危人群的针对性检查

D.可节约卫生资源

E.有较好的社会效益
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