Question

1．The truth（61）thattrees are vital to our life is not a secret．They provide us with food，wood and most（62）importantly（importance），oxygen．Now there is one more thing we can add to this list-blocking out harmful bacteria from water．
The discovery（63）was made（make） by a team consisting of scientists from the Massachusetts Institute of Technology （MIT） and high school students who were seeking a（64）natural（nature） water filter（过滤器）-one that would help communities in developing countries that do not have access to modern water filter systems．
The（65）researchers（research），led by Professor Rohit Karnik，decided to turn to trees for help because they could allow liquid to flow through，while（66）blocking （block） out air bubbles．
They began by cutting 1.5-inch-wide sections of tree bark from the branches of a white pine tree．The people related then tested the wood's filtering ability by pouring water containing red dye particles of different sizes through．（67）Totheir amazement，they found that it was effective in trapping all the articles．（68）Encouraged（encourage），the team conducted（69）anotherexperiment，this time with water（70）thatcontained bacteria．Sure enough，the sapwood held back 99% of the bacteria，allowing only 1% to flow through．

Answer 1

分析 本文讲述了树木在人类生活中的重要作用，它不仅能为人类提供食物，木材，甚至氧气，还能帮助净化人类的用水，这点已经被一所大学的研究者通过实验得到
了证实．

解答 61．that；考查关系代词，这是一个同位语从句，所以用that引导．
62．importantly；考查副词，这里用副词作状语，修饰谓语动词provide．
63．was made；考查被动语态，主语discovery与动词make是被动关系，所以要用被动语态，结合下文时态，用was made．
64．natural；考查形容词，这里用形容词形式natural修饰后面的名词water filter．
65．researchers；考查名词，结合下文语境，句子要用名词researchers（研究者）作句子的主语，因为不止一个研究者，所以用复数．
66．blocking；考查动词，while+doing 是一个省略了""主语+be"的固定结构，表示某一动作进行时另一动作正在发生，所以这里空格处应填blocking．
67．To；考查介词，"to one's+名词"是一个固定结构，"使人…的是"．
68．Encouraged；考查分词作状语，现在分词作状语表主动，过去分词作状语表被动；这里句子的主语the team 与动词encourage是被动关系，所以用过去分词作状语．
69．another；考查形容词，根据上下文语境，研究者已经做了一个实验，这里表示"又"做了一次实验，所以用another．
70．that；考查关系代词，这里是关系代词引导定语从句修饰前面的water．

点评 首先要通读全文，了解大意，抓住上下文语境所提供的信息，仔细分析带空格的句子，明确空格所要填的词义，词型和短语搭配给出所要填的正确形式，然后整
体阅读短文，核对答案．