简述列出一些可以改善幸福公司营运资金周期的方法。

小题1:Whose attitude(态度)  towards homework is positive(积极的) ?

A．William and Mary.

B．Chris and Sarah.

C．William and Sarah.

D．Mary and Chris.小题2: According to Mary's post, we know _______.

A．she likes homework a lot.

B．she thinks checking homework is worthless.

C．she hates students who don't do homework.

D．she hopes people can understand her hard work.小题3:Sarah is a_______.

A．parent

B．writer

C．student

D．teacher

条件刺激与无条件刺激在时间上的反复结合是（）

A．类化

B．恢复

C．分化

D．强化

民间借贷约定的利息高于银行同期同种贷款利率的( )倍时，签订的合同可确认为可变更、可撤销合同。

A．3
B．4
C．5
D．6

简要说明运用现金流量贴现法评估企业价值的基本思路。

设函数y₁(x)，y₂(x)，y₃(x)是二阶线性微分方程y"+a(x)y’+b(x)y=f(x)的三个不同特解，且

，则该微分方程的通解为______．