41. Some people believe that since oil is scarce, the ______ of the motor industry is uncertain.
[A] terminal [B] benefit [C] fate [D] estimate
42. To speed up the ______of letters, the Post Office introduced automatic sorting.
[A] treatment [B] delivery [C] transmission [D] departure
43. These overseas students show great ______ for learning a new language.
[A] enthusiasm [B] authority [C] convention [D] faith
44. The defense lawyer was questioning the old man who was one of the ______ of the murder committed last month.
[A] observers [B] witnesses [C] audiences [D] viewers
45. Politically these nations tend to be ______, with very high birth rates but poor education and very low levels of literacy.
[A] unstable [B] reluctant [C] rational [D] unsteady
46. The chairman was blamed for letting his secretary ______ too much work last week.