第21题: [单项选择]Our boss is taking everyone to the ballet tonight, and I need to make sure my new dress ______ for the occasion. A. has been cleaned B. should have been cleaned C. is being cleaned D. has been cleaning 参考答案:A 答案解析:句意:我们老板今晚要带大家去参加芭蕾舞会,我必须确定我的新长裙已经洗干净了。这里需要表示已经完成的状态,所以应该用现在完成时态,故选 A。