【填句补文】The Caribbean Islands form a chain that separates the Caribbean Sea from the rest of the Atlantic Ocean. ________. Many of the islands were formed by the eruption(爆发) of ancient volcanoes(火山)．Others are low-lying coral islands that gradually rose from the ocean.
A
They are famous for their warm, tropical climate and great natural beauty.
B
What would you see if you took a cruise to the Caribbean Islands?
C
They're like a long necklace that stretches between North and South America.
D
But life on the Caribbean Islands is not always paradise.
