下列选项中，属于期货交易的履约方式的是（）。
A.对冲平仓
B.到期交割
C.分期付款
D.背书转让
参考答案：A, B
There is a peaceful and calm _____ in the country, quite different from that of a big city.
A．climate
B．atmosphere
C．system
D．situation
