题目内容：

    Working on a farm and taking care of crops can be hot, time-consuming and difficult. Engineers have long wanted to build robots to lighten the load. But it has proved a difficult task. Robots that walk or roll along the ground can step on the easily damaged plants heavily. And they have to stop working when rain turns fields muddy.  “Tarzan”, however, could deal with some of those challenges.

Jonathan Rogers is a robotics expert at the Georgia Institute of Technology in Atlanta. When it comes to a farm environment, he realized robots would face many problems. “Many robots tend to get twisted(弯曲的) together or get stuck,”he says. What's more, he notes, "It's very hard to leave them out for long periods without a human helping them.”

What if the robot could move above the crops? Jonathan Rogers says, “The sloths(树懒)move from tree branch to tree branch to avoid having to walk around the forest floor. "Then his team set out to design a robot that could swing hand to hand along wires hung above the field. He named their invention Tarzan after the jungle-swinging character in a movie.

Tarzan is not the first swinging robot. Mark Spong, a robotics researcher at the University of Texas at Dallas notes that some teams have built robots that do gymnastics or copy mammals. But he says he admires Tarzan for its using swinging movement to save energy and the idea of building a wire structure to move around above crops.

Rogers first predicted that Tarzan could help farmers monitor crops with sensors (传感器) and cameras. But he also said future robots might take water to a particularly thirsty plant or fertilize one that needs nutritional support. And adding a third “hand”could allow such a robot to harvest fruits and vegetables. Finally the robot could move off the farm and into the city, helping deal with the traffic and security.

1.What worried the engineers when they built the farm robots?

A.They took up too much space.

B.They made the farming process slow.

C.They had difficulty exploring in fields.

D.They caused certain damage to crops.

2.What does Jonathan Rogers think about most farm robots?

A.They take much time to make.

B.They get out of date more easily.

C.They depend too much on people.

D.They get used to the environment slowly.

3.What attracts Mark Spong most about Tarzan?

A.Its strong wings. B.Its low cost

C.Its creative design D.Its powerful engine.

4.How did Jonathan Rogers feel about Tarzan’s future?

A.It could be found everywhere.

B.It could be put into more practical uses.

C.It could be used to do all the farm work.

D.It could be popular with working people in cities.