47. Fiber-optic cables can carry hundreds of telephone conversations ______.

　　A) simultaneously

　　B) spontaneously

　　C) homogeneously

　　D) contemporarily

　　48. The police were alerted that the escaped criminal might be in the ______.

　　A) vain

　　B) vicinity

　　C) court

　　D) jail

　　49. Whether you live to eat or eat to live, food is a major ______ in every family's budget.

　　A) nutrition

　　B) expenditure

　　C) routine

　　D) provision

　　50. Now a paper in Science argues that organic chemicals in the rock come mostly room ______ on earth rather than bacteria on Mars.

　　A) configuration

　　B) constitution

　　C) condemnation

　　D) contamination

　　51. As you have seen, the values of a nation's currency is a _____ of its economy.

　　A) reaction

　　B) reflection

　　C) response

　　D) revelation

　　52. In the Spring Export Commodities Fair the ______ of fine china attracted much attention of customers from all over the world.

　　A) succession

　　B) array

　　C) string

　　D) procession

　　53. We should make a clear _______ between the two scientific terms for the purpose of our discussion.

　　A) separation

　　B) discrimination

　　C) deviation

　　D) distinction