VHF系统用于()
A.长距离通讯
B.短距离通讯
C.超长距离通讯
D.长距离和短距离通讯
参考答案:B
The doctors insisted that the patient was in danger, and that he __________on immediately.
A.was operated
B.be operated
C.should operate
D.operated
对出口商风险最小的支付方式是()。
A.信用证
B.汇票
C.赊账
D.预付