1.Scientists do not know why dinosaurs became extinct,bue some theories postulate that changers in geography,climate,and sea levels were responsible.
科学家们不知道恐龙为什么灭绝，但是一些理论的假定，如地理条件、气候、和海水的变化是负有责任的。
2.The science of horticulture,in which the primary concerns are macimum yield and superior quality,utilizes inFORMation derives from other sciences.
园艺科学主要是涉及最大产出和最好质量，充分利用从其他科学中获取的信息。
3.Snow aids farmers by keeping heat in the lower ground levels,thereby saving the seeds from freezing.
雪帮助农民保持低洼土地的热量，因此避免了种子被冰冻。
