for oneself与by oneself

■for oneself 有两个用法：

1. 自己，亲自

You can judge for yourself. 你可以自己做出判断。

He demanded the right to decide for himself. 他要求得到自己做决定的权力。

2. 为自己，替自己

He made no complaint for himself. 他没为自己诉苦。

She’s wangled an extra week’s holiday for herself. 她多弄到一星期的假。

He acted without thought for himself. 他那样做的时候并没考虑到自己。

■by oneself 有三个用法：

1. 单独地，独自地（= alone）。如：

I like to travel by myself. 我喜欢独自旅行。

She was sitting by herself on a bench. 她独自坐在一条长凳上。

I often like to spend time by myself. 我平常喜欢独自消磨时间。

2. 靠自己，无他人帮助（without help）。如：

He did it by himself. 他是自己干的。

I studied by myself for all hour. 我自己学习了一个钟头。

She can mend the fridge by herself. 她能自己修理冰箱。

I managed to do it by myself. 我是自己做成这件事的。

3. 自动地（主要用于 by itself，意思相当于automatically）。如：

This is a machine that works by itself. 这是一台自动工作的机器。

The door opens by itself as you approach it. 当你靠近时候门就会自动打开。

The machine will start by itself in a few seconds. 机器在几秒钟后会自动开启。