投资乘数的计算公式是( )
A.国民收入/投资
B.投资/国民收入
C.国民收入的增加量/投资的最初增加量
D.投资的最初增加量/国民收入的增加量
参考答案:C
Not only his parents but also his brother ________ to the Summer Palace. They haven't
been back.
A.have been
B.have gone
C.has been
D.has gone