1. The probability that event A will occur is 0.5. The probability that event B will occur is 0.4. The probability that event A or B will occur is 0.8.

　　Column A：Probability that A and B both occur

　　Column B：0.1

　　A. The quantity in Column A is greater

　　B. The quantity in Column B is greater

　　C. The two quantities are equal

　　D. The relationship cannot be determined from the information given

　　2. Yesterday, at a certain school, the ratio of boys to girls was 1 to 3. Today, an equal number of boys and girls joined the school. The number that joined was greater than zero and no students left.

　　Column A: Ratio of boys to girls now

　　Column B: 1/3

　　A. The quantity in Column A is greater

　　B. The quantity in Column B is greater

　　C. The two quantities are equal

　　D. The relationship cannot be determined from the information given

　　参考答案：1C 2A