Question

某海滩在气温至少为 $80^{\circ} F$ 且晴朗时会很拥挤。六月十日该海滩不拥挤。关于这一天的天气条件，可以推出什么？

At a certain beach if it is at least $80^{\circ} F$ and sunny, then the beach will be crowded. On June 10 the beach was not crowded. What can be concluded about the weather conditions on June 10?

气温低于 $80^{\circ}$ F，且天气不晴朗。

The temperature was cooler than $80^{\circ}$ F and it was not sunny.

气温低于 $80^{\circ}$ F，或者天气不晴朗。

The temperature was cooler than $80^{\circ}$ F or it was not sunny.

如果气温至少为 $80^{\circ}$ F，那么那天晴朗。

If the temperature was at least $80^{\circ}$ F, then it was sunny.

如果气温低于 $80^{\circ}$ F，那么那天晴朗。

If the temperature was cooler than $80^{\circ}$ F, then it was sunny.

如果气温低于 $80^{\circ}$ F，那么那天不晴朗。

If the temperature was cooler than $80^{\circ}$ F, then it was not sunny.

答案：B

知识点：逻辑推理

难度评级：870

解答：

原命题是：若气温至少 $80^\circ F$ 且晴朗，则海滩拥挤。

因为海滩不拥挤，这两个条件不可能同时成立。因此气温低于 $80^\circ F$ ，或者天气不晴朗，或者两者都成立。

所以正确答案是 B。

The statement says that if the weather was at least $80^\circ F$ and sunny, then the beach was crowded.

Because the beach was not crowded, the two conditions could not both have been true. Therefore the temperature was cooler than $80^\circ F$ , or it was not sunny, or both.

Thus, B is the correct answer.

2011 AMC 10B 第 8 题

答案：B

难度评级：870

解答：

其他年份的第 8 题