by himself/for himself
 【问】 “Did you feed the baby milk?”“No，he can____. ”
 A. eat by himself B. feed for himself
 C. eat for himself D. feed by himself(TOEFL，71.10)
 《TOEFL、GRE解题词典》(P.145)说答案为eat by himself，而《TOEFL语法疑难详解》
 (P.194)则说答案为eat for himself。究竟哪个选项是正确的?
 【答】 就语法结构而言，选项eat by himself和选项eat for himself都是正确的。因为by oneself和for oneself都可用来表示“不依赖于别人帮助而独立地做某事”的意思。GPU和EPI对byoneself的解释是：unaided，without help。EPI对for oneself的解释是：by one's own efforts(asopposed to reliance on the help or efforts of others)。
 再考察一下下面的实例：
 1. Did you do your homework by yourself? (GPU)
 你是自己做的作业吗?
 2. I can study by myself. (London)
 我能自学。
 3. Then Robby can play by himself. (Macaulay)
 罗比能自己玩耍了。
 4. You and the girls may go，or you may send them by themselves... (Pride and Preju-dice，P. 2)
 你带着女儿去就行了，要不你索性打发她们自己去……
 5. I leave you to judge for yourself.(Mis)
 我让你自己来判断。
 6. Find out the meaning of the word Jor yourself in the dictionary. (ALD)
 你亲自查字典找出这个词的含义。
 7. Deserted by their parents，the children were left to fend for themselves. (Wood)
 孩子们被父母抛弃，只得自己谋生。
 8. There are many things which a disabled person cannot do for himself，and for which hehas to rely upon the help of others. (Wood)
 有许多事情是残疾人自己不能做而必须依靠他人帮助的。
 9. So great is our passion for doing things for ourselves，that we are becoming increasinglyless dependent on specialized labour.(NCE 3，P. 116)
 我们自己动手干的热情非常高，以致我们越来越无需依赖专职劳力了。