For the first red, you don't need an article before "relationship".
When you're saying "type of [word]", do not put any article before that word.
Example: "a type of device"
Not too sure about the "your back" parts. It could be your teacher does not like repition.
Also not too sure about "did". He probably wanted you to use the word "felt" instead of "did feel"
The first word of the last paragraph should be "in" not "at".
The red commas definitely do not need to be there.
Don't know why he marked "time to" and "to" red.
It's either internal or psychological
The answer is: figure out meaning based on what you already know and what the text says
To infer something from the passage, you need to read it and able to understand the meaning of the passage without actually put too much focus on the passage.
Passage inference could be considered as a reading skills. This usually tested when you do an SAT test to measure how much information you can gather from reading a certain text within a short period of time.
