中广网北京消息：据中国之声《全球华语广播网》报道，“爱美之心，人皆有之”。一些人陷入“容貌烦恼”,而铺天盖地的整形美容广告不仅让成年人心动，也诱惑着一些未成年人加入“爱美”大军，让整容的人群越来越低龄化。但是对于未成年人来说，稚嫩的皮肤、发育不完全的骨骼，都无法承受爱美之重。在此背景下，广州市出台《未成年人保护规定(草案)》。草案规定，除注册医生因医学上的理由外，禁止任何机构为未成年人进行整形手术。

    Most people have jobs. They go to 1 nearly every day. Some people are lucky. Either they have very interesting jobs or they earn a lot of 2. Most people are not so lucky. Either their jobs are a bit 3 or they don't get well 4.

    The most interesting jobs are often the most 5. People spend long time learning how to do them. Doctors study for 6 six years after finishing school. Airline pilots(飞行员) study longer. They have to learn to fly small airy craft first, and then 7 move up to bigger and bigger aircraft. Most airline pilots are at least 30 years old.

    Some 8 people have interesting and well-paid jobs. Many successful athletes(运动员) are usually under 35. Older people usually can't 9 these sports very well because they can't move fast enough.

    Most people work until they are 60 or 65 year old. Some people 10 retire. These people usually have very interesting jobs. Writers, artists, musicians and actors usually work until they die.

设P为椭圆$\frac{X^2}{16}+\frac{y^2}{9}=1$上的动点，则P到直线x+y﹣6=0的最小距离为（　　）

①当a＞0时，函数y有最小值，是____．

②当a＜0时，函数y有最大值，是____．