Until now, wires and cables for power and connectivity have limited the widespread adoption of sensor (传感器) networks by making them difficult and expensive to install and maintain. Battery-powered wireless networks can simplify installation and reduce cost. But their high power consumption and the corresponding need for regular battery replacement has made wireless networks difficult and costly to maintain. Nobody wants to replace hundreds or thousands of window sensor batteries in a large building on a regular basis.

The promise of wireless sensor networks can only be fully realized when the wiring for both the data communication and the power supply is eliminated. Doing so requires a true battery-free wireless solution, one that can utilize energy harvested directly from the environments. To facilitate the widespread deployment of wireless sensor networks, Greenpeak has developed an ultra-low-power communication technology that can utilize environmental energy sources such as light, motion and vibration. This technology, employing on-board power management circuits and computer software to monitor energy harvesters and make the best use of harvested energy, enables sensors to operate reliably in a battery-free environment.

Wireless sensor networks deployed in out offices and homes will have an enormous impact on our daily lives, helping to build a smarter world in which energy is recycled and fully utilized. These wireless platforms, equipped with advanced sensing capability, will enable us to better control our lives, homes and environment, creating a truly connected world that enables people worldwide to live in a more comfortable, safer, and cleaner environment.

49. By “human intervention” (Paragraph 2), the author refers to _____.

A the reduction of great energy waste in the environment

B the grasping of straightforward opportunities available

C the adoption of smart sensing and network technology

D acts like turning off lights when no one is in the room

50. Batteries are not an ideal energy source for sensor networks because they ____.

A contain metals that pollute the environment 

B have to be replaced from time to time

C require automatic recharging

D are difficult and costly to maintain

51. Battery-free wireless sensor networks are made possible by the fact that _____.

A the cost of using them has been drastically reduced

B there is energy in the environment to be utilized

C modern data communication consumes little energy

D their maintenance has been greatly simplified

52. According to the passage, GreenPeak _____.

A promotes the application of wireless sensor networks

B is the first company to install wireless sensor networks

C supplies batteries operating on harvested energy

D benefits handsomely from communication technology

53. The focus of Paragraph 4 is on the _____.

A replacement of batteries in harvesters

B monitoring of energy harvested from the environment