Directions: In this part there are 30 incomplete sentences. For each sentence there are four choices marked A, B, C and D. Choose the ONE answer that best completes the sentence. Then mark the corresponding letter on the Answer Sheet with a single line through the center.

　　16.In arithmetic the rules of addition are basic, and all the other rules are built on this __________.

　　A. basis B. bases C. base D. basises

　　17.Then the speaker __________ the various factors leading to the present economic crisis.

　　A. went for B. went after C. went into D. went on

　　18.Cake __________ of flour, sugar, egg and some other ingredients.

　　A. contained B. consists C. includes D. composed

　　19.Mr. Tyler asked his son to pay more __________ to his study.

　　A. notice B. attraction C. concern D. attention

　　20.He is __________ of an actor.

　　A. anybody B. anything C. somebody D. something