Eating organic food will not make you healthier, according to researchers at Stanford University, although it could cut your ____(expose) to pesticides（杀虫剂）. They looked at more than 200 studies of the content and ____(associate) health gains of organic（有机的） and non-organic foods. Overall, there ____(be) no difference in the nutritional content, although organic food was 30% less likely ____(contain) pesticides.

    The researchers looked at 17 studies comparing people who ate organic ____ those who did not and 223 studies ____ compared the levels of nutrients, bacteria, and pesticides in various foods. However, none of the human studies ran for longer than two years, ____(make) conclusions about long-term____(outcome) impossible. And all of the available evidence was____(relative) weak and highly variable, which the researchers said was unsurprising because of all the different variables.

    Dr Crystal Smith-Spangler, the lead researcher, said “Some believe that organic food is always healthier and more nutritious. But as ____ matter of fact there isn't much difference between organic and conventional foods, if you're an adult and make decisions based simply on your health.”

五（6）班图书角书架中的图书，故事书占 $\frac{1}{3}$ ，漫画类占 $\frac{1}{4}$ ，科技类占 $\frac{2}{5}$ ，其余为文体类，文体类占这些书的几分之几？

为了测定某轿车在平直路上启动阶段的加速度(轿车启动时的运动可近似看成是匀加速直线运动)，某人拍摄一张在同一底片上多次曝光的照片，如图所示，如果拍摄时每隔2 s曝光一次，轿车车身总长为4.5 m，那么这辆轿车的加速度为（   ）

亚欧大陆是世界上最大的大陆。