Many teachers believe that hands－on experience is the ____(good) way to learn. A group of students in the United States are putting that belief to the test. They ____ (success) designed and built a robot for discovering unexplored mines ____ the bottom of the sea. Students made the robot ____(answer) a challenge from the U．S. Department of Defense.

    The students recently tested the underwater vehicle ____(call) PerseusⅡin a 95－meter－long tank of water at the Stevens Institute of Technology.

    The robot costs about $15,000 to build. The students use a video game control to direct ____(it) movements in the tank. What's more, devices known as Japters ____ (able) the robot to go up, down and toward its target in the water. Video cameras on the robot send images back to a computer through a 13－meter－long cable. Perseus Ⅱ,____the students worked up to 20 hours a week to design and build, also has ____ set of lasers (激光), which are used to measure the size of an object.

    DeLorme supervised the project from ____(begin) to end. He says the specialized requirements of robots were demanding.