题目

Bees are unimaginably territorial (有地盘意识的), fighting to death to defend their home with painful stings (螫刺). But killer bees are particularly fierce. They appeared after African bees were imported to Brazil in the 1950s. By the 1980s, they had spread north to the United States, outgunning native bees along the way. Their massive attacks have killed more than 1,000 people.Mario Palma, a biochemist at Sao Paulo State University in Rio Claro, Brazil, who studies social behavior in bees, wanted to understand the basis of this aggression. So he and his colleagues swung a black leath某潜水艇可承受9.8×107Pa的海水压强，那么潜水艇在海中能下潜的最大深度是________m．（海水的密度为1.03×103千克/米3）．