Orbis is an organization which helps blind people everywhere．It has built an eye hospital inside an aeroplane and flown it all over the world with an international medical team．Samantha Graham，a fourteen-year-old schoolgirl from England，went with the plane to Mongolia．Samantha tells the story of Eukhtuul，a young Mongolian girl．

Last year，when Eukhtuul was walking home from school，she was attacked by boys with sticks and her eyes were badly damaged．Dr Duffey，an Orbis doctor，said that without an operation she would never see again．I thought about all the everyday things I do that she couldn't，things like reading schoolbooks，watching television，seeing friends，and I realized how lucky I am．

The Orbis team agreed to operate on Eukhtuul and I was allowed to watch，together with some Mongolian medical students．I prayed the operation would be successful．The next day I waited nervously with Eukhtuul while Dr Duffey removed her bandages．"In six months your sight will be back to normal，"he said．Eukhtuul smiled，her mother cried，and I had to wipe away some tears，too!

Now Eukhtuul wants to study hard to become a doctor．Her whole future has changed，thanks to a simple operation．We should all think more about how much our sight means to us．

50．What is the writer's main purpose in writing this text？___

A．To report a patient's cure．

B．To describe a dangerous trip．

C．To explain how sight can be lost．

D．To warn against playing with sticks．

51．What can a reader learn about in this text？___

A．The best way of studying medicine．

B．The difficulties for blind travelers．

C．The life of schoolchildren in Mongolia．

D．The international work of some eye doctors．

52．After meeting Eukhtuul，Samantha felt___．

A．proud of the doctor's skill

B．grateful for her own sight

C．surprised by Eukhtuul's courage

D．angry about Eukhtuul's expe