Previous studies showed that chimps and human children can solve similar tasks. In a 2011 study, chimps and kids found out that they could put water into a tube to reach a peanut that was floating in a small amount of water at the bottom.

　　【解题导语】　本文介绍了科学家通过实验对乌鸦智商的研究。

　　4．How did the crows get the snack in Sarah's experiment?

　　A．By breaking the tube.

　　B．By dropping in erasers.

　　C．By standing on the wood.

　　D．By removing the wood.

　　B　解析：细节理解题。根据第三段最后一句"The crows found out that they could drop the erasers into the tubes in order to raise the water level and get their snack."可知， 乌鸦能够把橡皮擦扔到管里， 使水位升高， 然后吃到零食。所以选B项。

　　5．What does the author mean by "the birds handled awkwardly" in Paragraph 4 ?

　　A．They were unable to tell different shapes.

　　B．They dropped objects only into narrow tubes.

　　C．They were not aware of the snack at first sight.

　　D．They mostly avoided the easier way to get the snack.

　　D　解析：推理判断题。从第四段可知， 实验中的乌鸦在面对粗细不同的管子时， 虽然只需往细管里投两次物体就可以够到零食， 而需往粗管里投大约七次物体才能够到零食， 但是乌鸦往往先去粗管那边， 而没有选择更容易获得零食的细管。由此可推知， 画线部分是说它们通常没有选择更容易的方式来得到零食。

　　6．What does the text mainly focus on?

　　A．Stories of Aesop's Fables.

　　B．The development of crows.

　　C．Crows' intelligence.

　　D．Human­animal communication.

C　解析：主旨大意题。根据第二段最后一句"The results suggest that the birds are, at least in some aspects, as smart as first­graders."以及下文中的实验可知， 整篇文章都是围