Scientists at MIT have managed to change ordinary spinach （菠菜）plants into natural sensors which can find chemicals used in bombs. The secret to giving spinach these special powers is nanotech （纳米技术），which is scientific area that deals with making or changing things that are extremely tiny.
"Ordinary spinach plants can be found everywhere and easy to store； like other plants, they normally take in carbon dioxide gas," the scientists say. "But actually they can sense small changes of soil and water potential and respond to them. If we tap into this point, there is a wealth of information to access. " That's what the scientists use to power their tiny experiments.
For this experiment,the scientists placed two different kinds of tiny nano-materials into spinach plants. To get them into the plants,the scientists put a liquid containing them on the bottom of the plant's leaves. As part of its natural process,the spinach plant pulls water through its roots and into its leaves. If the water contains certain chemicals used in bombs, the tiny sensors in the leaves make the nano-tubes,which,along with the sensors, were placed into the spinach plant before by the scientists, produce a slightly special kind of light. By watching the plant constantly using a camera attached to a cheap computer,the scientists set up a system that can send a warning email if chemicals from explosives are found in the water.
The computer the scientists used is about the size of a playing card. They say that in the future,their system could even use a cell phone with its camera changed slightly. Discovering chemicals used in bombs is just one of the many uses the researchers are exploring. They have used such plants to discover several other dangerous chemicals as well. From their point of view, there's no doubt that in the future, such systems could give farmers specific information about the health of the land and water on their farms.



Why do the scientists use plants to do the experiment？ ______

A. They are common in the dailylife.
B. They are environmentallyresponsive.
C. They absorb much carbondioxidegas.
D. They are small in size andeasytostore.

What's the function of the carbon nano-tubes placed into spinach plants？ ______

A. To control the camera.
B. To contain the liquid.
C. To fix the tiny sensors.
D. To give off plant light.

What can we say about the application of the experiment？ ______

A. It's diverse.
B. It's unexpected.
C. It's limited.
D. It's cheap.

What's the suitable title for the text？ ______

A. Spinach Is Sensitive to Chemicals in Bombs
B. Spinach Is taught to Send Warning Emails
C. Nanotech Helps Spinach Grow Healthily
D. Nanotech Protects Spinach from Danger