Listen to the following passage and fill in the blanks with the words you hear.[音频]When you think about dolphins, you might picture them swimming playfully near boats or doing ___1____ at a water park. Dolphins spend their whole lives in the water. These___2___ animals look like big fish, so it may surprise you to learn that they are mammals (哺乳动物). As all mammals do, dolphins ___3___ air. Dolphins must come to the water’s ___4___to breathe. A dolphin breathes through an___5___, called a blowhole, on the top of its head.Dolphins are considered ___6___ animals. In captivity, dolphins have shown that they can learn tricks and___7___. Scientists also discovered that dolphins have good ___8___ skills.