单项选择题National Reading Panel focuses on ______.
单项选择题The prison-house mentioned in the second paragraph must be ______.
单项选择题According to Landes, the main reason that some countries are so poor is that ______.
单项选择题One characteristic of the rich classes of a declining society is their tendency to ______.
单项选择题It can be inferred from tile passage that Giver is a book which ______.