题型：问答题 简答题 完形填空：从A 、B 、C 三个选项中，选择一个最佳答案填空，使短文意思完整。 What should we do to keep healthy? One important rule is to exercise 1 . The Smith family try to exercise every day. Mr. Smith 2 exercise in the morning because he must get to work at seven o'clock. But he runs every evening. He walks a lot, 3 . He goes to school on foot every day, and after school he 4 different sports with his friends. Mrs. Smith goes to a yoga (瑜珈) class 5 . But it wasn't always this 6 . Last year Mr. and Mrs. Smith used to (过去常常) take buses 7 , even to the drugstore two blocks away. They wouldn't walk. So they often go to the drugstore. But the Smiths all 8 better now. They believe they shouldn't be lazy. We 9 exercise every day, but we should try our best to exercise 10 often as possible. ( )1. A. often ( )2. A. may not ( )3. A. also ( )4. A. likes ( )5. A. in two weeks ( )6. A. way ( )7. A. somewhere ( )8. A. fell ( )9. A. don't ( )10. A. as B. sometimes B. can not B. either B. plays B. two or three weeks B. kind B. everywhere B. feel B. mustn't B. so C. never C. should not C. too C. watches C. twice a week C. result C. nowhere C. feel like C. needn't C. more 查看答案
题型：问答题 简答题 自1945年至1975年间，观察到做夜光表(同位素)的1000名女工中得骨癌者20例，而同期1000名话务员中得骨癌者4例。本研究方法是A．前瞻性研究B．回顾性研究C．临床试验研究D．实验流行病学研究E．现况调查研究 查看答案