They are ___ vacation in Sydney. [ ]
A. in
B. on
C. at
D. during
答案:B
全面结算会员期货公司向非结算会员收取的保证金,()期货交易所向全面结算会员期货公司收取的保证金标准。
A.不得高于
B.不得低于
C.等于
D.既可高于,也可低于
简述烟草产量与质量的关系。