By的基本含义
By是一个常用的介词，在英语中有多重含义。其中最基本的含义是“通过，靠着”，可以表示某种行动或方法是通过什么方式实现的，比如：
- She learned English by watching TV. 她通过看电视学习了英语。
- The news was brought to us by a messenger. 这个消息是通过信使传递给我们的。
By的进一步解释
除了表示通过、靠着之外，By还可以表示以下含义：
1. 表示时间：在时间上，By可以表示在某个时间之前，或者最晚在某个时间之前完成某事，比如：
- I need to finish this report by tonight. 我今晚之前要完成这个报告。
- The package will arrive by next Monday. 这个包裹最晚下周一到达。
2. 表示手段或方式：和“通过”类似，By还可以表示某种手段或方式，比如：
- I usually travel by train. 我通常乘坐火车旅行。
- He made the cake by following the recipe. 他按照食谱做了这个蛋糕。
3. 表示产生原因：By还可以表示某种原因或力量，比如：
- He was struck by lightning. 他被雷击了。
- The vase was broken by the cat. 这个花瓶被猫打翻了。
By的常见搭配及例句
1. By the way: 顺便说一下，用于在谈话中提出另一个话题，比如：
- By the way, have you heard about the new project?
- Oh, by the way, can you pick up some milk on the way home?
2. By all means: 一定，务必，表示诚恳希望对方采取某种行动，比如：
- By all means, come to the party if you can.
- If you need any help, by all means let me know.
3. By no means: 绝不，决不，用于表示某种观点或反对意见，比如：
- We are by no means ready to sign the contract.
- By no means should you give up your dream.
4. By and large: 大体上，总的来说，表示对一个问题总体评价，比如：
- By and large, I think the project was a success.
- The company is doing well, by and large.
5. By oneself: 独自，自己动手，表示某人独自或自己动手完成某事，比如：
- I did the presentation by myself.
- He cooked the dinner by himself.
结语
By是一个非常常见的英语介词，具有多重含义和用法。希望通过本文的介绍，读者们能够更好地掌握By的含义和用法。