证券公司、托管机构和推广机构可以根据市场的风险预测水平来规定附于成本收益的方式进行交易。 ( )
参考答案：错
As soon as the shoes that the boy wanted to buy were_____ in the store, the salesgirl called him. [ ]
A. present
B. possible
C. available
D. convenient
勘察数据是代表性数据具有一定（）性。
A.离散
B.相关
C.综合
D.准确
