第6题: [单项选择]A cartel is (an association) of producers in a (given) industry (whose) purpose is (restrict) competition. A. an association B. given C. whose D. restrict 参考答案:D 答案解析:将restrict改为to restrict。这是用不定式做表语的句子,to不能省略。该句的意思是,“卡特尔是在某个工业社会中一种生产者的组织,其目的是为了限制竞争”。