Roy works in London. It _____ him about half an hour to get to work by bus every day.
动词词义辨析。
表示“某人花费……时间去做……”，使用固定句型“It takes sb. +some time to do sth.”，可知缺少的谓语动词为takes，选C。
—Are you clear about the job of a policeman,Ben?
—Yes,to keep people _____ and the society in good order.
形容词词义辨析。
根据题干“the job of a policeman”可推断，警察的工作包括保护人们的安全，故所缺的词是safe“安全的”。
Michael visits many websites _____ about Chinese culture.
动词不定式用法。
表示“为了学习中国文化”，用动词不定式“to learn Chinese culture”表示目的，故选C。