题目

In conclusion,people around the world should be aware of the real situation of water shortage,protect the present water resources and explore (潜在的) ones scientifically. 答案：【1】potential一个布袋中放有红、黄、白三种颜色的球各一个，它们除颜色外其他都一样，小明从布袋中摸出一个球后放回去摇匀，再摸出一个球，请你利用画树状图法分析并求出小明两次都能摸到白球的概率．