36 In a series of tests that began last month, a research jet flew repeatedly into disturbed air hat 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 can be used in a wide range of areas
【参考答案】36. B37. C38. D39. A40. A
