<p>the theory is basically all the other content in the sat study guides 
It’s easier to explain maths, because you have to know like trigonometry, so they are saying that before you tackle those trig questions you might want to revise it for a bit.
For CR ex. study common mistakes that people often make like: is it ‘Carol and I…’ or ‘Carol and me…’?
That sort of thing</p>