259.
M: Hey, Mary! You have really been gone a long time. How did you do that?
W: Hi! Well, I talked with my teachers before I left about the work I would miss. Besides, my aunt in Denver made me study a lot there.
M: I thought she was your rich aunt.
W: Not very. But she didn't have any children to raise, so she does have some money, even though she was a teacher.
M: How was the holiday?
W: Cold, at least three of the days I went. And I saw so many people on the mountain on Washington's Birthday.
M: The beaches here were full on Washington's Birthday, too. It really was warm here, so lots of people went swimming.
W: Well, we should have stayed home that day. There were so many people. We took the train over to the mountain, so at least we didn't have to drive. It is a good thing we did-there were so many cars and buses, and no place to park anywhere.
M: Just like the beaches here.

答案解析：
(1) 正确答案为C。根据I talked with my teachers before I left about the work I would miss. Besides, my aunt in Denver made me study a lot there.我在离开前和老师谈了我可能会缺的课，另外，我在丹佛的阿姨也教我了很多。可知，男子是问玛丽怎么能缺这么多课。因此C项正确。
(2) 正确答案为A。根据I saw so many people on the mountain on Washington's Birthday.华盛顿诞辰日的时候我在山上看见了特别多的人；以及The beaches here were full on Washington's Birthday, too.华盛顿诞辰日那天这里的沙滩上也全是人。可推知，华盛顿诞辰日是国家法定假期，因此A项正确。
(3) 正确答案为C。根据We took the train over to the mountain.我们坐火车去的山上。可知，玛丽在华盛顿诞辰日那天坐火车去了山上，因此C项正确。