在一次历史研究性学习活动中，同学们搜集了某一时期陈独秀、李大钊、胡适、鲁迅等人的资料和文章。你认为这一学习活动的主题应是（　　）

阅读短文，判断正误。

    Mr. Black has a bigfarm. There is a vegetable garden on the farm. You can see carrots, green beans, potatoes and tomatoes. On his farm, there are many animals, too. There are ducks, sheep, hens, horses and goats. Mr. Black likes his animals. He feels(感觉) happy. My friends and I often go to the farm and play with the animals. Some friends like horses and some like goats. I like sheep. We often help Mr. Black clean the farm.