【题目】阅读下面材料，在空白处填入1个适当的单词或括号内单词的正确形式。
Dujiangyan was built over 2,200 years ago in what is now Sichuan Province in Southwest China. It is 【1】 oldest man-made water system in the world. This amazing engineering achievement is still used today to irrigate over 6,000 square kilometers of farmland, take away floodwater and provide water for fifty 【2】 (city) in the province.
In ancient times, the region in 【3】 Dujiangyan now stands suffered from regular floods 【4】 (cause) by the overflow from the Minjiang River. Li Bing, the governor of the region, together with his son, decided to find a way to solve the problem.
The simplest way was to build a dam, 【5】 this would ruin the Minjiang River. So Li designed a series of channels that would take away the floodwater while leaving the river flowing 【6】 (free). Better still, the extra water could be directed to the dry Chengdu Plain, making it 【7】 (suit) for farming.
Once the system was finished, no more floods occurred and people were able to live peacefully. Today, Dujiangyan 【8】 (admire) by scientists from around the world because of one feature. 【9】 (like) modern dams where the water is blocked with a huge wall, Dujiangyan still lets water flow through the Minjiang River naturally, making it possible for ecosystem and fish populations 【10】 (exist) in harmony.
在线课程【答案】
【1】the
【2】cities
【3】which
【4】caused
【5】but
【6】freely
【7】suitable/suited
【8】is admired
【9】Unlike
【10】to exist
【解析】
这是一篇说明文。文章介绍了四川省著名的水利工程-都江堰。都江堰始建于古代，主要目的是保护下游免受水患。
【1】考查冠词。由空格后的形容词最高级oldest判断出此处应该用定冠词the。故填the。
【2】考查可数名词的数。根据空格前的fifty可判断出此处用city的复数形式。故填cities。
【3】考查定语从句关系词。句意：古代，都江堰现在所处的地方常常会遭受从岷江溢出的洪水侵袭。分析句子结构可知此处是定语从句，先行词是the region指物，关系词在句中充当in的宾语，介词之后不能用关系词that，故用关系代词which。故填which。
【4】考查非谓语动词。句意：同上。分析句子结构可知，此处应该用非谓语动词作后置定语，逻辑主语和cause是被动关系，故用过去分词。故填caused。
【5】考查并列连词。句意：最简单的方式是修建大坝，但这样会毁掉岷江。分析句子结构可知此处应填连词；根据句意可知，前后部分是转折意义，故用并列连词but。故填but。
【6】考查副词。句中的flowing是现在分词，应该用副词修饰，free的副词形式是freely。故填freely。
【7】考查固定句型。句意：更妙的是，多余的水可以被引入干燥的成都平原，使得这个平原适宜耕种。根据固定句型make sth/sb+宾语补足语（名词，形容词，分词，介词短语）可知此处应该用suit的形容词形式suitable/suited。故填suitable/suited。
【8】考查时态和语态。分析句子结构可知，此句缺少谓语动词，主语“Dujiangyan”和admire之间是被动关系，故用被动语态，由today判断时态为一般现在时，主语是三单形式。故填is admired。
【9】考查介词。句意：不像现在那些由距墙隔断水流的大坝，都江堰的水可以自然而然地流过岷江。根据句意判断，此处应该用介词like的否定形式是unlike。故填unlike。
【10】考查固定句型。根据固定句型：make it + adj +for sb/sth to do 使得做某事对于某人来说是…的，可知此处应该用不定式形式。故填to exist。