Question

The boy did his homework with the help of his father in the past. But now he can do it alone.

1. A.
   for himself
2. B.
   on himself
3. C.
   by himself
4. D.
   with himself

Answer 1

C
for himself为自己； on himself靠自己；by himself通过自己，靠自己； with himself和自己。句意：在过去，这个男孩在他的父亲的帮助下做作业，但是现在他能够独自完成了。on himself前与搭配动词depend结合语境可知选Ｃ。
考点：短语辨析