Hxen.com's tips：Every day persisted can learn English well!-->■Learn English Everyday■
iceberg – n. a very large piece of ice floating in the ocean
shelf – n. a flat area of rock, sand, etc., especially underwater
disturb – v. to change something by moving it from its original position
ecosystem – n. everything that exists in a particular environment
species – n. a group of animals or plants that are similar and can produce off spring
dramatically – adv. very sudden or notable
