题干

已知反应X+Y= M+N为吸热反应,对这个反应的下列说法中正确的是(   )

A:X的能量一定低于M的,Y的能量一定低于N的

B:因为该反应为吸热反应,故一定要加热反应才能进行

C:破坏反应物中的化学键所吸收的能量小于形成生成物中化学键所放出的能量

D:X和Y的总能量一定低于M和N的总能量

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D

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    She sat at the picnic table alone. Recess(休息) was in full swing. She remained awkward around her classmates. She seemed unsure of what to do or say, yet I could see her eyes longing for acceptance. Many students had already decided that her friendship would not be worth the energy required to overcome the awkwardness. Others teased her. Most ignored her — except for one.

    Brianna, the class clown, was making the other students laugh, as usual. “Brianna, do you see Molly down there? Would you mind walking down there and inviting her to come up here with the rest of us?”

    Brianna sighed. I could tell she didn't want to sacrifice precious minutes of her own recess to do what I was asking of her, but I also knew her heart. She often thought of others before herself — a rare character for anyone, much less a kid.

    Knowing this choice was hard for her, I pulled out a D-buck, our class currency. Though bribery(行贿) was not the ideal way to handle this situation, I needed her cooperation.

    “Here, I'll pay you for your time.”

    She offered an insincere smile, grasped the green paper, and headed down the hill.

    As the rest of the children screamed and laughed, my eyes locked on Brianna as she neared the picnic table. Molly could be difficult, and I wouldn't have been surprised if she sent Brianna back alone, refusing her invitation. When she encouraged herself to a standing position, I sighed with relief.

    A minute later, 1 felt tap on my shoulder. “Here, Mrs. D.” She handed me the D-buck.

    “ Why?” I asked.

    “I shouldn't keep this.” Her eyes fell to her feet, guilt radiating from her quiet voice. “I don't want Molly to think 1 only went to get her so I could earn a muck. She's my friend.”

    A moment later, they were all laughing again, and who should I see among them, laughing for the first time that week? Molly.