下列实验中，颜色的变化与氧化还原反应无关的是

A．SO₂使酸性KMnO₄溶液褪色　

B．Na₂O₂投入酚酞溶液中溶液先变红后褪色

C．向FeSO₄溶液中滴NaOH溶液，生成的沉淀由白色变成灰绿色，最后变成红褐色

D．往紫色石蕊试液中通入氨气，溶液变蓝

. Which of the following is wrong?

This book is easy enough for ______.

A．a six-year-old child

B．a child of six years old

C．a child aged six

D．a six years old child