一宇宙飞船绕地球做匀速圆周运动，飞船原来的线速度是v₁，周期是T₁，机械能是E₁,假设在某时刻它向后喷气做加速运动后，进入新轨道做匀速圆周运动，运动的线速度是v₂，周期是T₂，机械能是E_2.则（   ）

玉米是吉林省重要的粮食作物，如图表示玉米植物体的结构层次，请据图回答问题：

卜老师认为，上世纪五、六十年代有一张看不见的铁幕阻隔了世界经济全球化的发展，这个时期的世界经济全球化其实只是“半球化”。可以支持卜老师观点的是（    ）

根据短文内容回答下列问题。

    Long, long ago there lived an old man. He had a very big orange tree in his garden. On the tree there were many fine oranges.

    One day the old man found one of the oranges was bigger than the others. It was as big as a watermelon. So he took the big orange to the king. The king was very happy and gave the old man a lot of money for it.

    When a rich man heard of this, he said to himself, "It is only an orange. Why did the king give him so much money? If I take my gold cup to the king, he will give me much more money for it."

    The next day when the king got the gold cup, he said to the rich man,"What a beautiful cup! I'll give you something for it. Please take the great orange."

下图中的两幅图比较，正确的是（    ）