题目内容：

While there are a few ways to make use of your old smartphone, one of the better ways is to convert into a dash cam (行车记录仪) that you can use on your bicycle. With the camera, you can record your rides, which is especially helpful if you are involved in a crash with another vehicle.

To use your smartphone as a dash cam on your bike, you will need to make sure it is properly secured to your bike. To do this correctly, you must take two strips of heavy-duty Velcro (a kind of cloth used as fastening) along with two pipe Clamps (管夹) and a flat corner brace (角撑) to properly attach it. You will start by attaching the comer brace to your smartphone.

Next, attach a Velcro strip to your phoned back. You will put the second strip on the end of the brace comer and cut any extra Velcro off and away from the brace. By using heavy-duty Velcro, you shouldn’t have to worry about the camera brace must be attached to the bicycle directly.

Take two pipe clamps so you can attach the part of the corner brace so the phone can be held up and used. The pipe    clamps must be positioned near the center of the handlebar, which will enable you to get a better picture when videotaping.

To run a dash cam app on your old phone, you will just need to download a dash cam app onto the old phone. You will then just start the app at any time you head out on the road. There is always the chance of flaws, but you will be giving yourself a way to protect yourself in a friendly, eco-friendly manner that is much less expensive than purchasing a dash cam.

1.What is the purpose of building a dash cam on your bike?

A. To make full use of an old smartphone.

B. To record the scenery while travelling.

C. To reduce an unexpected crash on the road.

D. To avoid unnecessary arguments in an accident.

2.What does the underlined word “it” in Paragraph 2 refer to?

A. The bike.    B. The pipe clamp.

C. The smartphone.    D. The flat comer brace.

3.What can we learn about a Velcro strip?

A. It will fix the camera firmly.

B. It is better to keep it as long as possible.

C. It is important for the flat comer brace.

D. It is best put in the center of the smartphone.

4.What can be inferred about the DIY dash cam from the last paragraph?

A. It is a perfect alternative to a purchased one.

B. It is beneficial to environment in some way.

C. It is a much more demanding job for the user.

D. It makes its owner friendly to other people.