题目内容：

Directions:Complete the following passage by using the sentences given below. Each sentence can be used only once. Note that there are two more sentences than you need.

Fed up with constantly having to recharge or replace batteries in your ever-expanding electronic devices? The solution may be just a few steps away.

“Energy harvesting” promises to power countless consumer devices, often with nothing more than your body's movement or heat.1..But many experts believe the market for the technology could explode due to electronic devices being developed for the Internet of Things.

Among the most basic forms of the technology is body power,2.Automatic watches have employed the concept for decades, for example, by winding themselves when their user moves their arm. Now the concept is being considered for a number of other devices.

In an contest seeking visionary ideas for wearable technologies, Intel awarded$5,000 for a concept to change the temperature difference between a person's body and a special piece of clothing they'd wear into electricity for mobile devices.

3.. Stanford University engineers are testing smart microchips that create electricity from ultrasound to power implantable devices that can analyze a person's nervous system or treat their diseases.

A textile research association in Spain is proposing to obtain electricity from radio waves that flow around everyone to power sensors sewn into clothes, which can monitor a person's heartbeat or other vital signs.

Obtaining stable energy from devices can be complex, however. For one thing, the motlon that generates the electricity has to be constant to be useful. Moreover, the amount of power the devices produce depends on the person using them, according to a Columbia University study, It determined that taller people on average provide about 20percent more power than shorter ones when walking, running or cycling.

4.. While such devices are expected to cost less than battery-powered alternatives when compared over many years ,experts say, people may continue buying ones with batteries merely because those would be cheaper in the short term.

A.Dozens of companies around the world already offer such products

B.Using sound to power devices is another energy-harvesting variation

C.It's also unclear how eagerly consumers might welcome energy-harvesting products,

D.With the Internet of things expected to combine billions of devices, we'll have to use energy harvesting.

E.When certain materials are squeezed or stretched, the movement of their atoms creates an electrical charge.

F.Research fim IDTechEx has estimated that annual global sales of energy-harvesting products could hit $.2.6 billion by 2024.