如图是元素x的原子结构示意圈．下列说法正确的是

      Traveling has been popular with people for a long time. Many of today's travelers are trying to find an unusual experience or adventure. Hiking may be a good choice.
       Instead of spending your vacation on a bus, in a hotel or sitting on the beach, you may want to try hiking. Hiking is a great way to travel. You will get close to nature and take exercise at the same time. Hiking is easy to do and doesn’t have to be very expensive. The basic equipments (设备) you need for hiking are simple: good shoes, clothes and a backpack. You can hike in the mountains, in a forest or along a river. You can also go for a hike in the city.
       Hiking is fun and exciting, but you shouldn't forget safety. Here are some basic tips for successful hiking:
      Don't hike alone.
      Bring water, a good map and a mobile phone.
      Wear a hat to protect yourself from the sun.
Answer the questions according to the passage.

将一圆形纸片沿半径剪开为两个扇形，其圆心角之比为3：4．再将它们卷成两个圆锥侧面，则两圆锥体积之比为（　　）