每日一题

Critical Reading>Sentence Completions

Choose the word or set of words that, when inserted in the sentence, best fits the meaning of the sentence as a whole.

While a "rock" is usually defined as ------- , or a combination, of one or more minerals, geologists often ------- the definition to include such materials as clay, loose sand, and certain limestones.

(A) a conglomeration . . limit
(B) an aggregate . . extend
(C) an element . . eliminate
(D) a blend . . restrict
(E) a product . . provide

答案和解析

答案：B

解析：

Choice (B) is correct. If these terms were inserted into the sentence, the sentence would read, "While a 'rock' is usually defined as an aggregate, or combination, of one or more minerals, geologists often extend the definition to include such materials as clay, loose sand, and certain limestones." An "aggregate" is the sum total of a combination of things, so a "rock" is an aggregate of one or more minerals. In addition to minerals, geologists feel confident including other materials such as "clay, loose sand, and certain limestones" in their definition of a rock; they "extend," or broaden, the definition.