thE Author's purposE oF writing this pAssAgE is to ______.
A．ArguE For tEAChing Bright AnD not—so Bright pupils in thE sAmE ClAss
B．rECommEnD pAir work AnD group work For ClAssroom ACtivitiEs
C．oFFEr ADviCE on thE propEr usE oF thE liBrAry
D．EmphAsizE thE importAnCE oF AppropriAtE FormAl ClAssroom tEAChing