单选题 (No wonder) that (man's) great dream has been someday to control the weather. The first step toward control is knowledge, and scientists have been (hard at work) for years trying to (keep track for) the weather.
【正确答案】 D
【答案解析】此题考查固定短语搭配keep track of的用法。意为“了解、掌握……的线索。应将keep track for改为keep track of。