海洋是人类未来开发利用资源的主要场所。下列操作不能用来淡化海水的是（）.
A.过滤
B.蒸馏
C.使海水结冰脱盐
D.多级闪急蒸馏
参考答案：A
The reason _______ he gave at the conference last week for his being carelessness was funny.
A．why
B．for which
C．that
D．for that
采取分期收款方式销售的货物，其纳税义务发生时间为( ) 。
A．将提货单交给买方的当天
B．按合同约定的收款日期的当天
C．货物发出的当天
D．办妥托收手续的当天
