___D__ some mammals came to live in the sea is not known.[ ]

___D__ some mammals came to live in the sea is not known.[ ] how some mammals came to live in the sea is not known, ____some mammals came to live in the sea is not known.能用whic __________ some medals came to live in the sea is not known. （共40题、总分40分）1.( ) some mammals came to live in the sea is no It is the largest mammals in the word that live on land.It l a good sailor is not known when the sea is clam and water is the sea is very deep in some places.some parts of the sea is The house is not big enough _____.A to live B to live in C f ----------it is to swim in the sea some children are lucky enough to live near the sea.为什么用live you can not imagine what fun it is to swim in the sea with m