Is your schoolbag too heavy? The e-schoolbag will help you. It is said that e-schoolbags are going to be brought into   43   in Chinese middle schools soon.
Heavy schoolbags have been a serious   44  for a long time. But the e-schoolbag will  45  . An e-schoolbag is  46   lighter than a usual schoolbag. Perhaps, the e-schoolbag should be   47   an e-textbook. It is a small computer for students. It is as   48   as a usual book,   49   it can still have all the things for study, such as textbooks, exercise books and so on which can be made   50   chips(芯片) like stamps. The students can read the text page by page on the screen, take notes, or even send e-mails to their teachers. They only need to   51  the right chip into the e-schoolbag. Then they can use it.
Some people say   52   e-textbooks can be easily broken, while others say it is not good for eyes. But only time will tell.

A．use B．useful C．used D．to use

A．idea B．problem C．question D．thought

A．work it out B．work out it C．work out D．work them out

A．very B．much C．too D．so

A．call B．calls C．called D．calling

A．small B．smaller C．smallest D．most small

A．and B．as C．or D．but

A．into B．from C．up D．of

A．bring B．get C．take D．put

A．if B．what C．that D．which