The ocean bottom, a region nearly 2．5 times greater than the total land area of the Earth, is even today largely unexplored．Until about a century ago, the deep-ocean floor was completely inaccessi
Once there was a poor little girl living near a forest.She had no family and no one to love her.So she often __1__ sad and lonely. One day, when she was walking in the for
π·(
)2×2=2π.