读下列各图，下图是澳大利亚代表性动物(    )

    Everyone knows that exercise is important. We all need to exercise. There are many ways to exercise. You can walk, run, swim, skate, or play ball games, but you should remember to exercise in the right ways.

        ①    Before you do any exercise, make sure to warm up for at least five minutes. During warming up, you should extend all parts of your body.

        ②      It's best to exercise twice each week. Thirty minutes each time is enough. Try all kinds of things until you find one, two or even three sports that feel right for you.

        ③    There are a lot of equipments (设备) at fitness centers. The equipments will help exercise your arms, legs and other parts of your body to make you fit. Some people buy equipments for their homes. But it is very expensive.

        ④     If you get hurt when you are doing exercise, don't play again until you are well.

某物质中只含有一种元素，则该物质不可能是（　　）

“通过建立无内部边界的空间，加强经济社会的协调发展和建立最终实现统一货币的经济货币联盟,……在国际舞台弘扬联盟的个性。”材料中的“联盟”指的是（   ）