股指期货的兴起与发展最主要的目的是向拥有股票资产和将要购买或出售股票者提供了转移风险的工具。( )
参考答案:对
用户程序中的输入、输出操作实际上是由哪一项完成
A.程序设计语言
B.编译系统
C.操作系统
D.标准库程序
I can hardly imagine the difficulty she had ______ enough evidence to prove that she was innocent.
A.collected
B.to collect
C.to have collected
D.collecting