46-50:教材的命運(yùn)

　　46、C)They cant connect professors and students as textbooks do

　　47、D) Falling sales

　　48、A) Reform its structures

　　49、C)Answer questions using their personal experience

　　50、B)They can learn in an interactive way

　　51-55:新型物種

　　51、D)It gets energy from both food and sunlight

　　52、A)The genes it captures from the sea plant algae

　　53、D)They can produce chlorophyll on their own

　　54、C)They don't usually function inside animal cells

　　55、B)They can survive for months without eating