题目

The point is that you should be happy with what you already have and not risk losing it by being____and trying to get more. A.cautious  B. considerate  C. sensitive  D.greedy 答案：D在一个盒子里装着只有颜色不同的若干黑、白、红三种颜色的珠子，其中红色珠子的颗数是白色的，黑色珠子的颗数是红色珠子的50%．如果从盒子中任意摸出一颗珠子，摸出黑色珠子的可能性是________．