如图，点A的坐标可以看成是方程组____ 的解．

Useful Information in Australia
Useful Numbers
All the telephone numbers are useful and free.
。Fire/ Police/ Ambulance(救护车)—000     Telephone information—12455
。Medical(医学的) Care—1300369359       Taxi—1800421113
Surfing the Internet
With so many Internet tearooms and public libraries, it's easy to surf the Internet in Australia.
Also it’s very cheap for you to surf the Internet.
。Public libraries offer free Internet every day even during public holidays.
。Many travel managers provide connection which is cheap or free.
Post Service
All post offices around the country offer post services(服务) so you can receive mails as you travel around the whole country.
。Post offices are usually open from Monday to Friday from 9 am to 5 pm.
。It costs 50 cents to send a standard（标准的） letter in Australia.
Public Holidays
On public holidays all shops are closed across Australia, so are banks and post offices.
。New Year's Day—1st January
。Australia Day—26th January
。Christmas Day—25th December

缺锌对人体健康造成的影响是（　　）

有下列五种物质：①2﹣甲基丁烷；②2，2﹣二甲基丙烷；③戊烷；④丙烷；⑤丁烷．它们的沸点由高到低的顺序正确的是（　　）

音乐会上正演奏小提琴协奏曲《梁山伯与祝英台》，优美的音乐是由于琴弦的____ 产生的，这动人的乐曲是通过____ 传到观众的耳朵里的。“余音绕梁，三日不绝”，这句话从物理学的角度看，说的是____ 现象。