下列各式中，合并同类项正确的是（       ）

阅读下面短文，从短文后各题所给的四个选项（A，B，C，和D）中，选出可以填入空白处的最佳选项。

You Did More Than Carry My Books

    Mark was walking home from school one day when he noticed a boy ahead of him had dropped all of the books he was carrying, along with a baseball bat and several other things. Mark 1 down and helped the boy pick up these articles. 2 they were going the same way, he helped to carry some of them for him. As they walked, Mark 3 the boy's name was Bill, that he 4 computer games, baseball and history, that he was having a lot of 5 with his other subjects and that he had just broken 6 with his best friend.

    They arrived at Bill's home first and Mark was 7 in for a Coke and to watch some television. The afternoon passed 8 with a few laughs and some shared small talk, and then Mark went home. They 9 to see each other around school, had lunch together once or twice, and then both ended up from the same high school. Just three weeks before 10, Bill asked Mark if they 11 talk. Bill 12 him of the day years ago when they had first met. “Do you 13 wonder why I was carrying so many things home that day?” asked Bill. “You see, I 14 out my locker(橱柜) because I didn't want to leave a mess 15 anyone else. I had planned to run away and I was going home to 16 my things. But after we spent some time together 17 and laughing, I realized that 18 I had done that, I would have 19 a new friend and missed all the fun we would have together. So you see, Mark, when you picked up my books that day, you did a lot more. You 20 my life.”

    I have read plenty of articles about self-improvement these past few months, and most of them tell you that you need to wake up and keep positive(积极的). When you wake up, you need to think that something great is going to happen today, and that you are going to have a great day. This kind of positive attitude(态度) is supposed to change your whole day.

    So this morning I woke up and decided to give it a whirl. The sun was shining brightly through my bedroom window, and it immediately gave me this warm feeling inside. I thought to myself, "Today is going to be a great day. One of the best days ever!" I got out of bed, took my morning shower and began to get dressed. I put on a pair of dress pants I have not warned in a while, followed by my dress shirt and that is when it began. I reached into my left pocket and pulled out what felt like some paper.

    You know that feeling of finding a $20 hill in your pants and it feels like free money? Because you forgot all about it and thought you never did?

    I pulled out a $100 bill and a $50 bill in the same pocket. It seemed like the best thing that had happened to me these days. Yes, $150 starts off my day! I'm sure if someone could have seen the smile on my face, they would have understood, I shouted in joy, with my poor dog looking at me like I was crazy!

    Start your morning off thinking you are going to have the best day ever and you just might! I really want to know what will happen next.