已知椭圆 $\frac{x^2}{9}+\frac{y^2}{5}=1$ 的左右焦点为F₁、F₂，点P为其上动点，点Q（3，2），则|PF₁|﹣|PQ|的最大值为（   ）

函数f（x）=x﹣3+log₃x的零点所在的区间是（　　）

    It can be hard to stay focused(专注的）all day at school.But ____ (luck),the subjects change,so you don't need to focus on the same subject all day long.Each subject ____  (last)for a limited time,____ you just need to focus for limited periods of time.There is usually a short break as you change books and other things for ____  new subject.

    At school,if your mind wanders(漫游)while you're listening or doing work at your seat, you'd better change the way you're sitting.In that way,you will become more ____  (comfort). Take a deep breath,so you can better listen to ____  is being said.

    To keep your mind on the work,talk to yourself about it.Ask yourself questions about what you need to do,then answer the questions and do the things you need to do.Do one thing at a time till you get it completely ____ (do).

    If the work is hard,don't just give ____ .Give it a try or ask for help.____  (put)it off won't help you do it,and that won't make the work any easier.Give ____ (you)brain a challenge--it's good exercise!