Dolphins’ Amazing Abilities
　① Dolphins have a number of abilities/which other aquatic animals do not have.// ② For example,/they can swim very fast/— around 40 kilometers an hour!// ③ They can dive very deep under the sea/without suffering from changes in water pressure.// ④ Their sense of hearing is much sharper/than that of humans.// ⑤ They send out high-frequency sound waves/to find out what objects are in the water.// ⑥ In addition,/they communicate by sound/and warn each other/when danger is near.// ⑦ Because of these abilities,/many scientists are interested in studying dolphins.//