Explanation: I'm thinking that you don't have to fill the blanks because there are two solutions offered after each fill in the blank but I can explain the rest.
These sentences are used to show common ways you can add "contrast" which is showing the difference between two or more things or comparison, where you are talking about the similarities between two or more things. The sentences shown (1,2,3,4) all show different ways you can write about contrast sentences and/or comparison sentences.
p.s. If you can clarify more on what you need help with, I'll be happy to answer!
