The police officer gave her a fine for driving too fast. 请问句中的driving 后边为什么加ing，语法实在是太烂了，不要笑话。

for是介词，介词后面要跟“名词/代词”作为其宾语，或者跟相当于名词/代词的结构，比如动名词、宾语从句等。如果后面是动词，不能直接跟在介词之后，而要变成+ing形式，这种doing称为“动名词”。动名词具有了名词的特性，就可以放在介词后作为其宾语了。
I'm interested in watching basketball,not in playing it.
I need to know something about raising cats.

ing动名词