单选题 The work ______ by the time you decide to cooperate with us.
A. will have been done B. was done
C. had been done D. has done

【正确答案】 A
【答案解析】[解析] 根据时间词“by the time”以及句意可知本句应该用将来完成时，又因句子表达的是被动意思，所以要用被动时。