题目

阅读下面的短文并用英语回答问题，并将答案写在答题卷上标有题号的横线上。 Tom Jenkins enjoyed fishing and spent most of his time by the river. He enjoyed being in the fresh air and being on his own. There was no one to trouble him and the time passed happily for him. Unluckily, he was not a very good fisherman. He either fished in the wrong place, used the wrong bait(鱼饵)or pulled in his line too quickly. Whatever the reason was, he never caught anything big enough to eat. However, he did not like to admit this to his wife. He thought she would complain if sh数列{an}的通项公式为an=2n-49，当该数列的前n项和Sn达到最小时，n等于（　　）A．24B．25C．26D．27