问题补充：
When a child realizes he should stand on his own feet, he has grown up.
A. stand up quickly
B. go somewhere on foot
C. get up by himself
D. depend on himself
答案：
A. stand up quickly
B. go somewhere on foot
C. get up by himself
(答案→)D. depend on himself
解析：stand on his own feet自主，相当于depend on himself依靠某人自己，句意：当一个孩子意识到他应该独立时，他已经长大了。故选D
