by oneself什么时候不用by

by oneself，这个往往在句子中作状语，可以将其省略，句子还是通顺的。它强调的是方式，即一个人、独自地。oneself在句子中作同位语、宾语、表语等。只有作同位语时，可以省略。

如the boy came to the shop himself中的himself是同位语。He isn't quite himself。他今天状态不好。中的himself不可以省略。He enjoyed himself at the party。派对上，他玩得很开心。宾语，不可以省略。

一、反身代词的基本形式

反身代词是 oneself根据所指词的人称、性别、单复数等的变化可以有 myself, himself, herself, yourself, itself, ourselves, yourselves, themselves 等形式。

二、oneself与himself

当one指人时，其相应的反身代词通常用oneself, 在美国英语中也可用himself：

One should not praise oneself [himself]. 一个人不应该自吹自擂。

三、反身代词的句法功能

1. 用作同位语(加强被修饰词的语气，紧放在被修饰名词后, 或句末)：

The box itself is not so heavy. 箱子本身并不重。

Mrs.Black herself is a lawyer. 布莱克太太本人就是一名律师。

You had better ask the driver himself. 你最好问司机本人。

Martin himself attended the sick man. 马丁亲自照顾病人。

Don’t trouble to come over yourself. 你不必费神亲自来了。

You yourself said so. / You said so yourself. 你自己是这样说的。

Never leave to others what you ought to do yourself. 不要把自己该做的事留给别人做。

2. 用作宾语(动词或介词的宾语)：

Take good care of yourself. 好好照顾你自己。

He has a right to decide for himself. 他有权为自己做出决定。

He made no complaint for himself. 他没为自己抱怨什么。

The child can dress himself. 这孩子能自己穿衣服了。

She finally gained control of herself. 最后她控制住了自己。

She could not make herself understood. 她不能使别人听懂她的话。

Everybody here has the influenza including myself. 包括我在内所有人都患上流感。

The child cried himself to sleep. 孩子哭着哭着睡着了。

She convinced herself that it was so. 她说服自己情况是这样的。

He had a couple of revolvers with which to defend himself. 他只有一两把手枪用来自卫。