Crops such as peas or soybeans put important minerals back into the soil, ______ it ready for crops that need fertile soil.

A．makes

B．to make

C．made

D．making

评价和判断技术方案在财务上是否可行和技术方案比选的主要依据是（）。

A.基准收益率

B.折现率

C.总投资收益率

D.财务内部收益率