完型填空。（每小题0.5，计5分）
Perhaps you ride a bicycle to school. Riding a bicycle can be great fun. Do you know how to ride a bicycle    41  ?
Careful boys and girls learn to ride their bicycle well    42   they go out on the road. How can you tell    43   you are a good rider or not?
If you can ride a bicycle in a straight line, you can ride well. If you can’t, you should practice riding    44   a safe place. To be safe on a bicycle, you    45   
to use both hands and both feet.    46   your feet on the pedals (脚踏) and your hands on the handle bars (把手) at all times.
Do you have a basket on your bicycle? If so, put your books and other things in the    47 .
You know that your bicycle is built for one person. It is not safe to carry anyone
   48   you.   49 is this so? Keep   50 safe by safety rules when you ride on a bicycle.

A. safe	B. safely	C. save
A. before	B. after	C. until
A. that	B. how	C. whether
A. in	B. at	C. to
A. must	B. need	C. may
A. Keep	B. Make	C. Let
A. box	B. bag	C. basket
A. to	B. for	C. with
A.Why	B. What	C. How
A. yours	B. you	C. yourself