题目内容：

    Wang Zhonglin started playing table tennis only four years ago. But last year, he and other researchers came up with a clever way to up their game; Build a smart table.

Now they've built a prototype (样品). It can measure where a ball lands, how fast the ball's going, where it's headed and the angle it was traveling. The table can do that because its special wood surface forms the top layer (层) of a novel self-powered sensor. The data it acquires could guide players to perform better.

Importantly, the new smart table won't need a battery to detect the ball. When a ball hits the wood, it sets off a chain of events that can both produce a small electric current(电流) and record measurements of the ball's behavior.

What makes the new game table truly unique is its use of wood as one of the layers because wood can produce electricity by rubbing against it. But Wang's group realized they couldn't rely on wood that comes directly from a tree. It's too hard and too easily broken. They needed a kind of wood that could bend. So they boiled the wood in chemicals for seven hours. Then they dipped the wood in boiling water. Once it came out of the boiling baths, the wood bent easily.

The scientists then cut the treated wood into small squares. Each measured just 1.8 inches on a side. Those squares became the top layer. Beneath this wood, they added a layer of metal to conduct electricity. They attached that layer to a metal wire. Then, instead of using a table-tennis ball, they hit the surface with a type of hard plastic. When it registered an electric current, they moved on to building a test table.

“It is amazing. To me, self-powered sensors of wood is the first move toward using energy harvesting and sensing in sports," said Askar, an engineer in Canada. And it need not end with table tennis, he added.

1.What can we know about Wang's invention?

A.Its battery lasts very long. B.It sells well in the market.

C.It can accelerate the ball's speed. D.It can judge the ball's direction.

2.Why did Wang use wood surface?

A.It is easy to get. B.It can produce electricity.

C.It is hard enough. D.It is environmentally friendly.

3.What was the wood like after being treated?

A.It bent easily. B.It shrunk greatly.

C.It broke easily. D.It became harder.

4.What can be inferred from Askar's words?

A.Sports meets will end with a table tennis match.

B.The technology will be used in other sports.

C.Table tennis isn't the first to use self-powered sensors.

D.The table tennis ball will be self-powered in the future.