单元话题导读
Killer Whales
You are about to be introduced to the world’s biggest family! Killer whales are social whales that live in groups called pods①. A pod can include 40 whales, with each member being able to grow as big as a school bus. Imagine going out for a swim and seeing 40 buses swimming towards you，that’s what it would be like to meet a pod of killer whales!
Killer whales can grow to 23 to 32 feet in length② and reach a weight of up to 6 tons. They are easy to identify③ due to④ their black and white markings and the large dorsal fin⑤ on their back. Killer whales must have smiles because their teeth can grow to four inches in length.
Killer whales use their big teeth to help themselves capture⑥ prey⑦，but don’t worry！Even though they’re called killer whales, people are not typically⑧ attacked by these whales. Killer whales eat squid⑨，octopuses⑩，sharks, and all types of fishes. They can even grab? dinner off the shore if a seal? or a bird gets too close to the water’s edge.
①pod n．一小群
②length n．长度，时间的长短
③identify vt.确定；鉴定
④due to由于
⑤dorsal fin n．背鳍
⑥capture vt.俘获；夺得；捕捉
⑦prey n．猎物
⑧typically adv.典型地；有代表性地
⑨squid n．乌贼；鱿鱼
⑩octopus n．章鱼
?grab vt.攫取；霸占
?seal n．海豹
