①设A，B为两个定点，K为非零常数，若|PA|﹣|PB|=K，则动点P的轨迹是双曲线．

②方程2x²﹣5x+2=0的两根可分别作为椭圆和双曲线的离心率

③双曲线 $\frac{x^2}{25}-\frac{y^2}{9}=1$ 与椭圆 $\frac{x^2}{35}$ +y²=1有相同的焦点．

④已知抛物线y²=2px，以过焦点的一条弦AB为直径作圆，则此圆与准线相切

其中真命题为____（写出所以真命题的序号）

    For years people have enjoyed following the life of Garfield the cat. Garfield is a popular comic book character, known for being lazy and fat. But the cat was back in the news recently for something you might not expect.

    A man in the United States changed the  genderof Garfield to “none” on the cat's Wikipedia ( 维 基 百 科 ) page. After that lots of people got angry and keptchanging Garfield's Wikipedia page. They argued about whether the cat was a boy,girl or neither.

    Wikipedia finally locked the page to stop people editing( 编辑) it. Jim Davis, Garfield's creator, settled(解决) the argument.

    “Garfield is male,” he simply told the Washington Post. The 71-year-old artist said he liked working with animals because they didn't have to be old, young, boys or girls. He was angry that some people cared so much about Garfield's gender.

    It seems like quite an unnecessary argument to have. But it is not the only recent example of argument about gender.

To celebrate International Women's Day in Australia earlier this year, the city of Melbourne made 10 traffic lights with a figure( 人形) dressed in a skirt. They were designed to celebrate Women's Day and give them more confidence in public.

    But not everyone thinks the idea is necessary. Some people think it is important for women to be treated fairly in Australia, but that this idea is silly.

    “I'm all for doing anything we can for gender equity(公平), but really?” Melbourne mayor( 市长)

    Robert Doyle told the Herald Sun. The mayor said this idea is more likely to be laughed at than bring respect to women.