关于葡萄胎超声表现,下列哪项是正确的
A.子宫小于孕期B.双侧卵巢正常C.子宫大于孕期D.官腔内无血流显像E.卵巢黄素囊肿是诊断葡萄胎的唯一征象
参考答案:C
Apart from his monthly salary as a sales manager, he also gets a travel ________ that covers hotel bills. [ ]
A. insurance
B. circumstance
C. allowance
D. competence
水力漩流器几个控制回路的作用?