Complete the following passage with the words or phrases in the box.Each can only be used once.（将下列单词或词组填入空格.每空限填一词）

A.understood B.In my opinion C.What\’s more D.dream E.higher

Except that parrots can speak,some else have also shown signs of （1）______ intelligence.An African Gray Parrot named Alex had a vocabulary of some 150 words and could do simple math.（2）______ ,it could distinguish（辨别） seven colors and five shapes,and （3）______ the meaning of zero.Overall,he had the intelligence of a five-year-old human.This means that parrots having conversations with humans is no longer a （4）______ that is strictly （严肃地） for the birds.