新疆闻名全国的农产品，正确的一组是（　　）

You _____ jump onto a bus while it is still moving. It is too dangerous.  

根据短文内容，判断下列各句正误。
      Hong Kong has about forty public beaches. Some of them are very famous around the world. People can go there for a swim. You can go to them by bus. To go to some beaches you must take a boat.
    You will swim there without danger if you remember these instructions:
    Never swim alone.
    Never go out in a boat if you cannot swim.
    Never swim after a meal or when you feel hungry or tired.
    Don't stay in the water too long.
    Remember: A red flag means that it is dangerous for anybody to go into the water. A blue flag means that it is dangerous for children.

某离子化合物的晶胞如图所示。阳离子位于晶胞的中心，阴离子位于晶胞的8个顶点上，则该离子化合物中阴、阳离子的个数比为(　　)