在以下四个交易环节均会产生退回需进行退汇处理:支付交易、实付付款交易、实付返款交易、退货(批量和联机)交易。()
参考答案:对
It’s important ______ us to learn from others. It’s wise ______ you to learn from him.
A.for; for
B.of; of
C.for; of
D.of; for
何谓数字通信?数字通信偶哪些优缺点?