Come and see the India elephants and the new tigers from America. The bears are waiting to meet you, and the monkeys from China are waiting to throw（扔） things to you. The lovely dogs from Australia are waiting to laugh at you. The giraffes from Brazil are waiting to look down on you.
Tickets                             Open time
Grown-up:（成人）$2.00             9:00a.m—4:00p.m
Children :over 12 $1.00               Except（除）Friday
Under12 Free(免票)                  10:00a.m—3:00p.m
Keep the zoo clean!
Don't touch(触摸) , give good food or go near the animals!

俗话说：“人生不如意者十有八九”。这表明（      ）

 下列工具属于费力杠杆的是（　　）