Students who get tired of looking at the four walls of a classroom might like to take the nature course being offered by Carvel College again this summer．Groups of about a dozen students each，led by an experienced guide，will go on ten-day camping trips to the mountains to study the plants and animals that grow and live there．
Students carry their own things，which includes sleeping bags，warm clothing，food and water，and other useful tools．And what do the students do all day？Well，as soon as the sun comes up，they eat breakfast and start climbing up the mountain trail to the next campground，which is five to ten miles away．As the students take notes，the guide points out different plants and animals alongside the trail．The climb is usually over by early afternoon，so the group spends the rest of the day resting or swimming in a mountain lake．Before dinner each night，they all come together and discuss the day's activities．
At the end of the course，the students write reports using the information they have collected．But they don't mind at all．What they do mind is leaving the beauty of the wilderness and the good friends they've made to return to their normal lives in the city．

46．What can the course offer to the students？
A．Better grades in tests．
B．Free vacations in mountains．
C．A different learning experience．
D．Better chance to study in Carvel College．
47．How far does a student have to walk throughout the course？
A．About five to ten miles．
B．About two hundred miles．
C．About fifty to one hundred miles．
D．About sixty to one hundred and twenty miles
48．What do the students have to do before dinner？
A．Wash themselves up in a mountain lake．
B．Attend classes by the experienced guide．
C．Write about what they see along the trail．
D．Review what they learn through discussion．
49．What can we tell about the course？
A．They will change campgrounds everyday．
B．The students have to learn all by themselves．
C．Pens and books will be useless in the course．
D．Carvel College will provide everything for the students．
50．From the last paragraph we know the students are ．
A．serious with the final report
B．unwilling to go back to the city
C．looking forward to returning home
D．too tired to stay in the course any longer．