In the passage the author's attitude towards "mixed-ability teaching" is ______.

A．The general public has been fully conscious of the consequences of glohal warming.
B．Political measures have been taken to deal with the consequences of global warming.
C．The team of professionals are only indifferent to the consequences of global warming.
D．The experts are well aware of the consequences of global warming.

A．Mixed-ability teaching prevents pupils from getting more knowledge.
B．There are more advantages than disadvantages to stream pupils.
C．We should emphasize pupils' academic ability rather than other abilities.
D．Work in groups is helpful to master various abilities.