静液压系统安全阀是当高压油管内工作油管内工作油压超过()kpa时,高压油直接回封闭油箱,从而缓和系统冲击,避免过载。
参考答案:170
Assume the holder of a long futures position negotiates privately with the holder of a short futures position to accept delivery to dose out both the long and short positions. Which of the following statements about the transaction is most correct The transaction is:()
A. also known as delivery.
B. also known as an exchange of physicals.
C. the most common way to close a futures position.
锅炉上水要求