A、A picnic. B、The river. C、A friend. D、The weather. D男士问女士明天天气如何，并说一想到明天要和Jack去河边野餐就很兴奋；女士表示天气预报说明天天气晴朗，温度在25℃左右。由此可知，对话双方正在谈论天气

W: How about our academic evaluation of this subject at the end of this term, Prof. Smith?
M: Grading is determined by your performance in the midterm and final test, periodic quizzes, a research project and classroom participation.
Q: What can we learn about the students from this conversation?

M: Linda, what will the weather be like? I’m so excited when thinking of going to the river for a picnic with Jack tomorrow.
W: According to the weather forecast, you can expect fair skies for most of the day with a temperature of about 25°C .
Q: What are the two speakers talking about?