my first is in"snow"but not in ice ,my second is in "rose"an

写全了么...问题都不给全...真难为人...
My first is in "snow"but not in"ice",
My second is in both"rose"and "rice",
My third is not in"pencil"but in"paper",
MY whole is a place where there is a lot of water.
第一个字母是 s 第二个字母是 e 第三个是 a 谜底是sea 海洋...