砂轮的()是指磨粒、结合剂、气孔的比例关系。
参考答案:组织
When I handed the report to John,he said that George was the person ________.
A.to send
B.for sending it
C.to send it to
D.for sending it to
汇票的基本特征除流通性、无因性、要式性、返还性外还包括()
A.安全性
B.高效性
C.发展性
D.可追索性