How do you choose the right preposition in front of "which"?
For example:
1) When Defoe was nearly sixty years old he turned to fiction and wrote the greater work by which he is remembered. (why is "by")
2)It It is sometimes said that the next best thing to eating food is talking about food. If this is true, we need the vocabulary with which to do it! ( Which stand for what? I'm confused)
How do you choose the right preposition in front of "which" when you are writing or speaking? I found that it's really hard for me to make my own sentence with it even if I understand when I'm reading.