下列关于风险控制手段的说法正确的是：（）
A.主动减少外汇风险头寸
B.能够提高风险收益
C.通过套期保值减少风险
D.建立防范基金降低风险
参考答案：A
mn2（x-y）3+m2n（x-y）4分解因式后等于______．
—Tom, the workers _____our new library already.
—Really? I'll go there and borrow some books. [ ]
A. decorated
B. are decorating
C. have decorated
D. were decorated
