sat2010.5月真题 阅读section8 12题 want=lack? 话说 原文第24行,the memorie

sat2010.5月真题 阅读
section8 12题 want=lack? 话说 原文第24行,the memories of inncocent people may suffer这句话什么意思?for want of a record of the facts to which those who come after us can appeal.这句话怎么读?
section5 13题 b是怎么立即看出来的 过后能发现就太晚了