题目

 There are few visitors in this area at this time of year,_______?    A. are there     B. aren’t there  C. are they         D. aren’t they 答案：A一项工程，甲乙丙三人合做8天完成．现由甲乙合做1天后，剩下的由丙独做15天完成．求丙的工作效率．