Pigeons（鴿子）may be considered mice of the sky，but some scientists have found greater value in these urban birds：the blueprint for a new generation of flying machines．
   Birds can transform the shape of their wings by fanning out their feathers or moving them closer together．Those adjustments allow birds to cut through the sky more flexibly than rigid drones（無人機）．Now，using new insights into exactly how pigeons' joints control the spread of their wing feathers，researchers have built a robotic pigeon．This research paves the way for creating more light aircraft，says Dario Floreano，a roboticist in Switzerland not involved in the work．
   "What's really cool about this robot is that you can make adjustments in a robotic wing that you could never do when studying flight in a bird"，says David Lentink，an engineer and biologist at Stanford University．A controllable robotic pigeon solvesthat problem．In flight tests，Lentink's team observed that bending only the fingers of one wing eased the robot into a banked turn-offering the first evidence that birds may sometimes use just their fingers to direct in flight．In a second study，Lentink's group used their robotic wing design to confirm another insight into bird flight：how gaps are prevented from forming between feathers on extended wings．
   This is the best set of robotic wings yet for testing how birds adjust their flight feathers to move through the air，says Tyson Hedrick，a biomechanist．But "there's plenty of room for improvement．" For instance，a future flying robot could include a shoulder joint to investigate how waving a bird's wings up and down influences flight，he says．

（1）What is the newly-found worth of pigeons？

D

D

A．They help study other species．
B．They protect other urban birds．
C．They provide proof of mice's harm．
D．They inspire a new aircraft．
（2）What is Dario Floreano's attitude to the research？

B

B

A．Negative．
B．Positive．
C．Neutral．
D．Critical．
（3）What do the underlined words "that problem" in paragraph 3 refer to？

B

B

A．Pigeons in flight can hardly be observed．
B．People can't make adjustments in birds' wings．
C．It is difficult for pigeons to make a banked turn．
D．Pigeons fail to control the spread of their wing feathers．
（4）Where does the text probably come from？

D

D

A．A travel journal．
B．A travel brochure．
C．A science fiction．
D．A science magazine．