9 In arithmetic， a number stands for the size of a set of things.

　　A measures

　　B estimates

　　C cancels

　　D represents

　　10 Some species of bacteria and fungi thrive on simple compounds such as alcohol.

　　A mix with

　　B do well on

　　C exist in

　　D float on

　　11 Why do you want to throw away those books?

　　A imitate

　　B discuss

　　C extract

　　D discard

　　12 The Pullman Strike of 1894 tied up transportation and was finally ended only by government intervention.

　　A relied upon

　　B hindered

　　C linked with

　　D imitated

　　13 Although a herd of African elephants may have up to one thousand members， Asiatic elephants live in bands of five to sixty animals.

　　A as many as

　　B more than

　　C fewer than

　　D at least

　　14 Prohibition in the United States ushered in an era of crime and corruption.

　　A introduced

　　B caused

　　C used

　　D upset

　　15 The Spanish， French， Dutch， and English all vied for North American territory.

　　A arrived on

　　B competed for

　　C disposed of

　　D sailed for

　　答案：1 D 2 D 3 B 4 C 5 B 6 B 7 B 8 D 9 D 10 B 11 D 12 B 13 A 14 A 15 B