对于备兑开仓，需要合约标的的多少百分比充当保证金（）。
A、0.2
B、0.5
C、0.8
D、1
参考答案：D
句型转换。
1. Sally is the best girl in her class.
Sally is ______ ______ ______ ______ girl in her class.(改为同义句)
2.My uniform is not the same as his. (改为同义句)
My uniform is______ ______ his.
3. Amy likes to travel around the world by air. (对划线部分提问)
______ ______ Amy like to travel around the world.
电磁式控制继电器由（）组成。
A.电磁系统
B.触头系统
C.灭弧装置
D.反力系统
