完形填空。 Perhaps you ride a bicycle to school. Riding a bicycle can be great fun. Do you know how to ri de a bicycle 1 ? Careful boys and girls learn to ride their bicycle well 2 they go out on the road. How can you tell 3 you are a good rider? If you can ride a bicycle in a straight line, you can ride well. If you can't ,you should practise riding 4 a safe place. To be safe on a bicycle, you 5 to use both hands and both feet. 6 your feet on the pedals and your hands on the handle bars at all times. Do you have a basket on your bicycle? If so, put your books and packages in it. Then you can 7 both hands on the handle bars. You know that your bicycle is built for one person. It is not safe to carry anyone 8 you. 9 is this so? Keep 10 safe by safety rules when you ride on a bicycle. Watch where you are going at all times. (     )1. A. safe (     )2. A. as soon as (     )3. A. that (     )4. A. in (     )5. A. must (     )6. A. Keep (     )7. A. keep (     )8. A. to (     )9. A. Where (     )10. A. it B. safety B. before B. how B. on B. need B. Make B. make B. for B. Why B. yours C. safely C. after C. what C. at C. may C. Let C. let C. with C. What C. you D. save D. until D. whether D. to D. can D. Get D. get D. by D. How D. yourself