天山 4-39

T-4-Q39

Five
hundred million different species of living creatures have appeared
on Earth, nearly 99 percent of them vanishing.

1. Five
       hundred million different species of living creatures have appeared
       on Earth, nearly 99 percent of them vanishing.

   
           

2. Nearly
       99 percent of five hundred million different species of living
       creatures that appeared on Earth have vanished.

   
           

3. Vanished
       are nearly 99percent of the five hundred million different species
       of living creatures that appeared on Earth.

   
           

4. Of
       five hundred million different species of living creatures that have
       appeared on Earth, nearly 99 percent of them have vanished.

   
           

5. Of
       the five hundred million different species of living creatures that
       have appeared on Earth, nearly 99 percent have vanished.

   
           

并没有其他理由使用完成时，说是强调太牵强。

8.   A huge flying
reptile that died out with the dinosaurs some 65 million years ago, the
Quetzalcoatlus had a wingspan of 36 feet, believed to be the largest
flying creature the world has ever seen.

(A) believed to be

(B) and that is believed to be

(C) and it is believed to have been

(D) which was, it is believed,（C）

(E) which is believed to be

我认为选E，B的that从句中用了一般过去时，表示这些动物原先出现在地球上，现在已经不在了，而题目中只说了99%的灭绝了，这样不符合逻辑，而现在完成时则可以表示动作发生在过去，并延续到现在，表示了出现的过程，更符合语句的逻辑意思：指从过去到现在出现的动物。