87.The word darted" in paragraph 5 can be best replaced by ()."

25.According to Papousek, the pleasure babies get in achieving something is a reflection of ().

24.The babies would “smile and bubble” at the lights because ().

23.In Papousek’s experiment babies make learned movements of the head in order to ().

22.Papousek noticed in his studies that a baby ().

21.According to the author, babies learn to do things which ().

20.Which of the following is the main idea of the passage? ().

19.Cats sleep much more than horses do partly because cats ().

18.According to the author, we cannot sleep well when we ().

17.Evolution has programmed man to sleep at night chiefly to help him ().

16.The author uses the example of the robot in space exploration to tell us ().