1.The board of the company has decided to ________ its operations to include all aspects of the clothing business.

　　A) multiply

　　B) lengthen

　　C) expand

　　D) stretch

　　2.His business was very successful, but it was at the ________ of his family life.

　　A) consumption

　　B) credit

　　C) exhaustion

　　D) expense

　　3.First published in 1927, the charts remain an ________ source for researchers.

　　A) identical

　　B) indispensable

　　C) intelligent

　　D) inevitable

　　4.Joe is not good at sports, but when it ________ mathematics, he is the best in the class.

　　A) comes to

　　B) comes up to

　　C) comes on to

　　D) comes around to

　　5.Doctors warned against chewing tobacco as a ________ for smoking.

　　A) relief

　　B) revival

　　C) substitute

　　D) succession

　　6.When carbon is added to iron in proper ________ the result is steel.

　　A) rates

　　B) thicknesses

　　C) proportions

　　D) densities

　　7.You should try to ________ your ambition and be more realistic.

　　A) reserve

　　B) restrain

　　C) retain

　　D) replace