红色的为答案，能解释下为什么吗，初学者不太理解。

1.Which of the following is always incorporated in an interest rate?

A  Inflation premium

B  Risk premium  

C  Market premium

D  The rate of pure time preference

E  Internal rate of return

2.Which of the following is always incorporated in an interest rate?

A  Inflation premium

B  Risk premium  

C  Market premium

D  The rate of pure time preference

E  Internal rate of return

3. Which of the following is incorporated in the nominal rate but  is never incorporated in the

real rate of interest?

A  Risk premium

B  Internal rate of return

C  The rate of pure time preference

D  Inflation premium