In a series of tests that began last month, a research jet flew repeatedly into disturbed air over the mountain ridges (山脉) near Pueblo, Colorado. The lidar detector spotted turbulence between 3 and 8 kilometers ahead, and its forecasts of strength and duration corresponded closely with the turbulence that the plane encountered.
Bogue says that he had "a comfortable amount of time" to fasten his seatbelt. The researchers are planning to improve the lidar's range with a more powerful beam. The system could be installed on commercial aircraft in the next few years.
36 What does "clear-air turbulence" probably mean? (Paragraph 1)
A A not very rough storm.
B Unexpected disturbed air.
C A kind of visible storm.
D A storm over mountain ridges.
37 In December 1997, a United Airlines flight hit unexpected rough air
A causing a lot of damage to the plane.
B throwing its passengers out of the cabin.
C resulting in heavy casualties. D forcing the pilot to make an emergency landing.
38 The turbulence detector can tell the severity of the turbulence by measuring
A the speed of the plane.
B the speed of the light.
C the number of particles in the air.
D the changes of the particles' speed.
39 We can infer from the fifth paragraph that
A the lidar detector can successfully forecast turbulence.
B researchers are not sure about the effectiveness of the lidar detector.
C passenger planes will be used in further experiments.
D no more test flights are needed.
40 The last paragraph tells us, among other things, that
A the lidar detector needs improvement.
B many airlines are interested in the system.
C passengers often forget to fasten their seatbelts.
D the lidar detector c
