His brother aims to be of his parents by the time he is twenty.A. innocentB. beneficialC.

问题补充：

His brother aims to be of his parents by the time he is twenty.

A. innocent

B. beneficial

C. invisible

D. independent

答案：

A. innocent

B. beneficial

C. invisible

(答案→)D. independent

解析： 词义辨析。innocent 无辜的，无罪的；beneficial有益的；invisible 看不见的；independent独立的。句意：他弟弟打算在他20岁时能够离开父母独立。所以选D。