狭义的金融市场投资主要指（）。
A.银行存款
B.买卖黄金
C.买卖债券、股票、基金凭证、各种票据
D.买卖外汇
参考答案：C
函数f（x）=x3-6x+a的极大值为______，极小值为______．
After a few years' hard work, they ______ in finish building the big bridge.[ ]
A. developed
B. succeeded
C. searched
D. observed
