单选题 {{B}}Directions:{{/B}} Read the following text. Choose the best word(s) for
each numbered blank and mark A, B, C or D on ANSWER SHEET 1.
In his 1979 book, The Sinking Ark,
biologist Norman Myers estimated that {{U}}(1) {{/U}} of more than 100
human-caused extinctions occur each clay, and that one million species
{{U}}(2) {{/U}} by the century's end. Yet there is little evidence of
{{U}}(3) {{/U}} that number of extinctions. For example, only seven
species on the {{U}}(4) {{/U}} species list have become extinct
{{U}}(5) {{/U}} the list was created in 1973. Bio-
{{U}}(6) {{/U}} is an important value, according to many scientists.
Nevertheless, the supposed mass extinction rates bandied about are {{U}}(7)
{{/U}} by multiplying {{U}}(8) {{/U}} by improbables to get
imponderables. Many estimates, for instance, rely a great deal
on a "species-area {{U}}(9) {{/U}} ", which predicts that twice as many
species will be found on 100 square miles {{U}}(10) {{/U}} on ten square
miles. The problem is that species are not distributed {{U}}(11) {{/U}}
, so bow much of a forest are destroyed may be as important as {{U}}(12)
{{/U}} . {{U}} (13) {{/U}} , says Ariel Lugo,
director of the International Institute of Tropical Forestry in Puerto Rico,
"Biologists who predict high {{U}}(14) {{/U}} rates {{U}}(15)
{{/U}} the resiliency of nature". One of the main muses of
extinctions is deforestation. According to the Consultative Group on
International Agricultural Research, what destroys tropical trees is not
commercial logging, {{U}}(16) {{/U}} "poor farmers who have no other
{{U}}(17) {{/U}} for feeding their families than slashing and burning a
{{U}}(18) {{/U}} of forest". In countries that practice
modern {{U}}(19) {{/U}} agriculture, forests are in {{U}}(20)
{{/U}} danger. In 1920, U. S. forests covered 732 million acres. Today they
cover 737 million.
【正确答案】
A
【答案解析】an average平均数。number数字；sum总数，金额；amount数量。a sum of意为“一笔”，一般后面接金钱，也可接其他不可数名词。an amount of意为“许多”，后接不可数名词。根据后面出现的each day可以确定应用an average。句意：生物学家诺曼•迈尔斯在其1979年所著的《正在沉没的方舟》中估计每天人为原因造成的物种灭绝超过100种，到本世纪末会有100万个物种灭绝。
【正确答案】
B
【答案解析】would disappear。语法测试点为过去将来时。这个句子中that one million species…是estimated的宾语从句。主句动词用一般过去时，宾语从句中表示将来的动词应用过去将来时。很多同学误选[D]，注意此处不是虚拟语气。
【正确答案】
A
【答案解析】any where near接近于。little表示否定，可排除“somewhere near”和“something like”。anywhere可以表示数量不确定，大概在…之间，故A项正确，这里是指数量上的关系，而不是时间的关系，因此不能用anytime when。句意：不过并没有什么证据表明已灭绝的物种接近这个数目。
【答案解析】In addition另外。语篇关系题，上一段谈到一个问题，这一段又谈到另外一个问题，因此应用表示补充说明的关联词。But但是；Instead代替，而是；As a result结果，因此。句意：另外，波多黎各热带森林研究所主任阿莱尔·卢戈还说，生物学家高估物种灭绝速度的同时也低估了自然界的恢复力。