2 . Were it not for g_______, which brings them down to the earth, arrows would continue to fly forward forever in a straight line. (根据首字母单词拼写)

6 . 汉译英
1. a famous ________ 一位著名的宇航员
2. the selection ________ 选择过程
3. ________ and physical training 身心训练
4. an ________ answer 一个聪明的回答
5. the secrets of the ________ 宇宙的秘密
6. escape Earth’s ________ 摆脱地球的引力
7. make ________ to carry people 制造载人的交通工具
8. ________to be a explorer 决定做一个探索者
9. the Sputnik ________ “旅伴一号”卫星
10. ________ the satellite 发射卫星

9 . 英译汉

1. absence ________________
2. gravity ________________
3. astronaut ________________
4. float ________________
5. cupboard ________________
6. mission ________________
7. bother ________________
8. occupy ________________
9. ceiling ________________
10. evaluate ________________