阅读理解。
A lot of crime is against bicycles. About 150,000 bicycles are stolen every year and most are never found.
You can prevent this happening by following a few careful steps.
Basic Security
Do not leave you bicycle in out-of-the-way places. Always lock your bicycle when you leave. Secure (栓牢)
it to lampposts (灯柱) or trees. Take off smaller parts and take them with you, such as lights and saddles (车
座).
Locks
Get a good lock. There are many different types in the shops. Buy one that has been tested against attack.
Ask for a recommendation from a bike stop.
Marking
Security marking your bike can act as a deterrent to a thief. It can also help the police find your bicycle. It
should be clearly written and include you postcode and your house or flat number. This will provide a simple
way to identify your bicycle.
Registration
There are a number of companies who will security mark your bicycle for you. They will then put your
registration number and personal details on their computer database. Then if your bicycle is found it will be
easy to contact you.
Finally keep a record of the bicycle yourself: its make, model and registration number. You can even take
a photograph of it. This will prove the bicycle belongs to you.
1. Which part gives you information on how to lock up your bicycle when you leave it? [ ]
A. Locks.
B. Marking.
C. Registration.
D. Basic Security.
2. The underlined phrase "act as a deterrent to a thief" means _____. [ ]
A. help you recognize your bike
B. help the police find you bicycle
C. stop someone stealing your bicycle
D. stop you worrying about your like
3. The article advises you to keep a record of your bicycle _____. [ ]
A. in the bike shop and your computer
B. in a police station and a security company
C. in a security company and your university
D. by yourself and in a security company
的瞬时冲量，则物块在车上滑行的路程s=？。（设物块与车挡板碰撞时没有能量损失）