why ? because it's a personal question about your personal life. what you understand more.
This is an example :
I think I am better at pre-reading because I've been better at going through a text to locate key ideas before carefully readinf a text or a chapter of a text from start to finish.
I can say I got better at post-reading. How ? well I've gotten better at summarizing , reflecting and question what I've read. It is good that I now know more about post-reading because it can show I am good at comprehension.
Milk contains sugar, fat and water. It is a mixture because sugar, fat and water are all substances and as a result, the combination of those three, makes it a mixture.