S5. Elementary education often relies on grouping students to________.

A．Check to see if anyone lazes out.
B．Do the group members’ work.
C．Check to see if it’s done correctly.
D．Check to see if everyone is there.

A．There are too many underdeveloped countries in the world.
B．Underdeveloped countries have low level of industrial development.
C．Different governments have different views on the question.
D．Even developed countries have complex problems.