题目内容：

第二节 下面文章中有五处需要添加首句，请从A到F的六个选项中选出符合各段主题的句子，完成第31-35题。（其中一项为多余选项。）

How to ride a bicycle in traffic

Cycling in traffic is something that seems dangerous but can be quite safe as long as you obey the rules of the road and exercise alertness (机敏)and common sense. Here are some tips for you.

1.A helmet(头盔) won’t prevent accidents. But it can save you from serious head injuries if you are in an accident. That’s why it’s always safer to wear it when cycling.

2. So always have lights if it is not very bright out, and if you cycle in the evening, reflective clothing is a great idea. The more obvious you are to drivers, the less likely they are to hit you.

3.Start from the easy streets. Pick some quiet back streets and get used to being around cars and other road traffic Gradually build up your stamina(耐力) on larger roads by practicing on them on quiet days.

4. Always ride with the traffic. Stay off sidewalks, stop for red lights, stop at stop signs, and obey all other traffic signs. Don’t run red lights no matter how many other cyclists do it. Your good habits can help improve others’ safety awareness.

5. If you need to talk on your cellphone, stop and pull over. Don’t listen to an MP3 player or radio. Some cars are very difficult to hear, so you need to pay careful attention to not get run over by them.

A. The wearing of helmets is a requirement in many countries.

B. If you’re an inexperienced cyclist, it is not a good idea to throw yourself in the heavy traffic.

C. Make sure you are comfortable with your bike.

D. You should always pay attention to the rules of the road.

E. Most accidents happen when drivers haven’t noticed a cyclist.

F. Avoid doing things that will affect your ability to hear cars coming up behind you