质押合同成立的有效要件有（）
A、须经公证
B、须经登记
C、须出质人和质权人签订书面合同
D、须将质物移转于质权人占有
参考答案：C
We hope that as many people as possible _____ join us for the charity show tomorrow. [ ]
A. need
B. can
C. must
D. should
蒸馏酒
