[单项选择]

In his 1979 book, The Sinking Ark, biologist Norman Myers estimated that (1) of more than 100 human-caused extinctions occur each day, and that one million species (2) by the century’s end. Yet there is little evidence of (3) that number of extinctions. For example, only seven species on the (4) species list have become extinct (5) the list was created in 1973.
Bio (6) is an important value, according to many scientists. Nevertheless, the supposed mass extinction rates bandied about are (7) by multiplying (8) by improbables to get imponderables.
Many estimates, for instance, rely a great deal on a "species-area (9) ", which predicts that twice as many species will be found on 100 square miles (10) on ten square miles. The problem is that species am not distributed (11) , so how much of a forest am destroyed may be as important as (12) .
(13) , says Ar
A. equation
B. calculation
C. coordination
D. classification

In his 1979 book, The Sinking Ark, biologist Norman Myers estimated that (1) of more than 100 human-caused extinctions occur each day, and that one million species (2) by the century’s end. Yet there is little evidence of (3) that number of extinctions. For example, only seven species on the (4) species list have become extinct (5) the list was created in 1973.
Bio (6) is an important value, according to many scientists. Nevertheless, the supposed mass extinction rates bandied about are (7) by multiplying (8) by improbables to get imponderables.
Many estimates, for instance, rely a great deal on a "species-area (9) ", which predicts that twice as many species will be found on 100 square miles (10) on ten square miles. The problem is that species am not distributed (11) , so how much of a forest am destroyed may be as important as (12) .
(13) , says Ar
A. disappeared
B. would disappear
C. will disappear
D. would have disappeared