I'll give you one quote from each chapter you need from The Great Gatsby and let you or other editors find second ones.
In chapter seven, page 141 of my edition, Tom says:
Go on. He won't annoy you. I think he realizes that his presumptuous little flirtation is over.
This quote signals that Tom has won and Gatsby has lost. Daisy has refused to declare that she never loved Tom and always loved Gatsby. She will be staying with Tom and Tom knows it. He is so sure of himself that he lets Daisy ride home with Gatsby.
In chapter eight, page 158, the narrator writes:
She [Daisy] wanted her life shaped now, immediately--and the decision must be made by some force--of love, of money, of unquestionable practicality--that was close at hand.
That force took shape in the middle of spring with the arrival of Tom Buchanan.
This is a flashback that explains how Daisy and Tom first got together. It explains why Daisy did what she did.
In chapter nine, page 187, Nick is speaking to Tom and he relates some of the dialogue:
"Tom," I inquired, "what did you say to Wilson that afternoon?"
He stared at me without a word and I knew I had guessed right about those missing hours. I started to turn away but he took a step after me and grabbed my arm.
Tom then explains why he told Wilson that Gatsby owns the car that killed Myrtle. The fact that Tom goes after Nick shows his continued insecurity and his need to explain himself.
'But it's too hot!' insisted Daisy, on the verge of tears. 'and everything's so confused. Let's all go to town!'
I love this quote for a couple of reasons. It sums up what has happened figuratively thus far in that Daisy's relationships are too hot... she's keeping up with a marriage and an affair and this is the point at which all of them are about ready to go to New York. Tom just figured out she's with Gatsby. This is the climax of the story and everything is pretty confusing. In true Daisy fashion, she changes the subject.
"Of course, she might have loved him for a minute, when they were first married - and loved me even more then, do you see?"
Jay says this to Nick and it proves how dillusional this love or fantasy has made him. Daisy had and is returning to a relationship with her husband Tom at this point. Jay won't accept it. Gatsby is trying to rationalize her affection or love for him, but enough has happened, he just needs to get over her. At this point she is choosing familiarity and stability over the outrageousness that their relationship could present.
Gatsby believed in the green light, the orgastic future that year by year recedes before us.
Nick utters this as the narrator in part of his summation or closing remarks. I think it shows that he saw Gatsby as a man who worked toward a goal or at least the potential of a goal. Obviously he achieved it for a time, but at what cost. This is the moment in the story at which point you as a reader have to truly considered what you learned, and if all you needed to learn was indeed achieved. What do you long for? What lengths would you go to in order to accomplish it? Would you cross moral lines?