参考答案

正确答案：C
解析：这道题属推论题，目的是考查读者对文章中语句的理解程度。If the Greek mathematicians had not applied themselves to investigation of conic sections，zealously and without the least suspicion that it might someday be useful，it would not have been possible centuries later to navigate far from shore．这是一个虚拟语气的句子，如果能理解它的意思，作答此题就不难了。当时的数学家们认为他们的研究可能将来有用，但对于研究的具体价值却不太清楚。