Listen to the following passage and fill in the blanks with the words you hear. 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.