大神帮忙解释一下

deibo

Q39:

Five hundred million different speciesof living creatures have appeared on Earth, nearly 99 percent of themvanishing.

• Five     hundred million different species of living creatures have appeared on     Earth, nearly 99 percent of them vanishing.
• Nearly 99     percent of five hundred million different species of living creatures that     appeared on Earth have vanished.
• Vanished     are nearly 99 percent of the five hundred million different species of     living creatures that appeared on Earth.
• Of five     hundred million different species of living creatures that have appeared     on Earth, nearly 99 percent of them have vanished.
• Of the     five hundred million different species of living creatures that have     appeared on Earth, nearly 99 percent have vanished.
  

   Answer: E  

   此题appear的时态一定要用完成时吗？                                                                                                                    

Gil_0_

是的，更準確地說，是因為have vanished 使用了完成時，所以appear必須同樣使用完成時以表示appear出現在vanish之前

deibo

有道理，谢谢！回复的太晚了

MissSugarW

并不是Appear在vanish之前吧，是因为还有1%的物种仍然appear才用的完成时。