Sydney Tower
Address: 100 Market St, Sydney
Phone: 02 9333 9222
Fax: 02 9333 9203
Open time: 9:00 a.m. t0 10:30 p.m. (Saturdays to 11:30 pm)
Ticket: $60 (for an adult) $30 (for a child)
Website: www.sydneytower.com.au
How to get there: train to Town Hall Station and a short walk along Market Street
How to book tickets: by phone/fax or through the web
Attractions: Sydney’s best views are just the beginning! Sydney Tower takes you to the highest point
above Sydney for exciting 360° view of our beautiful city.

现有爬行、哺乳、飞行三类动物，其中蛇、地龟属于爬行动物；狼、狗属于 哺乳动物；鹰、长尾雀属于飞行动物，请你把下列结构图补充完整．

①二次三项式ax²+bx+c的最大值为4；

②4a+2b+c＜0；

③一元二次方程ax²+bx+c=1的两根之和为﹣1；

④使y≤3成立的x的取值范围是x≥0．

其中正确的个数有（   ）