3．Wildlife in Decline
The populations of Earth's wild vertebrates （脊椎动物）have declined by 58% over the past four decades，according to the Living Planet Report 2016published by the World Wildlife Fund．
Climate change and activities such as deforestation and poaching（偷猎）are in large part （21）to blame（blame） for the decline．If the trend continues，by 2020，the world （22）will have lost（lose） two-thirds of its vertebrate biodiversity．"Sadly，there is no sign yet （23）that this rate will decrease，"the report says．
"Across land，fresh water and the oceans，human activities are forcing wildlife populations to the edge，"says Marco Lambertini，director-general of WWF International．
The Living Planet Report is published every two years．It aims to provide an assessment of the state of the world's wildlife．The 2016 study included 3700 different species of birds，fish，mammals，amphibians and reptiles around the world．The team collected data from more than 3000 sources，including government statistics and surveys （24）carried （carry） out by conservation groups．They then analyzed （25）how the population sizes had changed over time．
Lambertini said some groups of animals had done worse than others．''We do see particularly strong declines （26）in the freshwater environment．For freshwater species alone，the decline stands at 81% since 1970．This is related to the way that water （27）is used（use） and taken out of freshwater systems，and also to the fragmentation（分裂）of freshwater systems through dam building，for example．"
The report also highlighted other species，such as African elephants，（28）which nave suffered huge declines in recent years，and sharks，which are threatened by overfishing．
（29）In spite of all the terrifying facts，however，some conservationists say there is still hope．"One of the things that I think is the most important is that these wild animals haven't yet gone extinct，"said Robin Freeman，head of the Zoological Society of London．"On the whole，（30）they are not dying out，and that means we still have opportunities to do something about the decline．"
分析 1970～2020年间，全球野生动植物的数量下降了58%．野生动植物所面临的最大问题就是栖息地的逐渐减少．而无节制的伐木，农耕，各种原因导致的淡水生态系统的减少等等是导致野生动植物栖息地减少的主因．
解答 21．to blame 考查动词不定式．be to blame for意为"应对…负责（应因…而受责）"，是固定搭配．
22．will have lost 考查动词时态．根据句中时间状语，用将来完成时态．
23．that 考查同位语．sign后接的同位从句this rate will decrease是完整的，要用连词that引导．
24．carried 考查过去分词．surveys与carry之间是动宾关系，用过去分词短语carried out by conservation groups作后置定语．
25．how 考查连词．analyze后接的宾语从句缺少方式状语，用how作方式状语，同时引导宾语从句．
26．in 考查介词．"在…环境里"，用介词in．
27．is used 考查动词时态和语态．water与use之间是动宾关系，且表示现在的情况，用一般现在时的被动语态，主语the water是不可数名词，助动词用单数形式is．
28．which 考查定语从句．分析句子结构可知这是一个定语从句，先行词African elephants在从句中作主语，用关系代词which．
29．In spite of 考查介词．根据句意：尽管所有这些可怕的因素．用介词短语In spite of．
30．they 考查代词．they指代上文中提到的these wild animals．
点评 在一篇200词左右的语篇（短文或对话）中留出10处空白，部分空白的后面给出单词的基本形式，要求考生根据上下文填写空白处所需的内容或所提供单词的正确形式，所填写词语不得多于3个单词．要做好语法填空题，理解短文是解题的前提，扎实的词汇、句型和语法知识是基础，英语国家的背景知识是必要的补充．考生须灵活运用语法知识，如单词词性、单词时态、名词单复数、连接词、代词、冠词等判断各空白处应填写的内容．答完后，还要通读全文，核对所填单词形式是否正确，是否符合语境．
