单选题 Once the baby has mastered the idea that space is three-dimensional, it ______ out and begins grasping various kinds of objects.
  • A. shouts
  • B. reaches
  • C. aims
  • D. pull
【正确答案】 B
【答案解析】B项reach out“伸出手”。A项shout out“大声喊叫”；C项aim不与out搭配；D项pull out“拔出”。根据题意，应选B项。