题目内容：
There were year-round programs in the 19th century because of
A．the need of science B．the need of research
C．economic reasons
D．political reasons
参考答案：
答案解析：
单选题：There were year-round programs in the 19th century because
- 题目分类：英语四级
- 题目类型：单选题
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B．the need of research
C．economic reasons
D．political reasons