化学反应可视为旧键断裂和新键形成的过程．化学键的键能是指气态_爱下问搜题

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问题选择题

化学反应可视为旧键断裂和新键形成的过程．化学键的键能是指气态原子间形成1mol化学键时所放出的能量．现提供H₂燃烧反应中有关物质的化学键键能：H-H Q₁kJ/mol；H-O Q₃kJ/mol；O₂分子内氧原子间的键能为Q₂kJ/mol．根据图中物质变化的四个过程，则下列说法正确的是（　　）

A．①过程吸收能量为Q₁+Q₂

B．②过程放出能量为2Q₃

C．③过程能量变化为4Q₃-（2Q₁+Q₂）

D．④吸收能量为4Q₃

答案

答案：C

完形填空

完形填空（共15题，每题1分，计15分）
Five years ago, when it was time for my cousin to start college, my 75-year-old grandfather, Rex, decided to do the same. He went to    1 , taking classes twice a week until his death last summer.
As a student, my grandfather spent countless hours in his office   2    and completing assignments. Although he was twice as    3     as his professors, he loved going. He said,“You can never 4    too much, no matter how old you are.”He loved everything about school. Learning new things was truly his passion.
My grandfather’s will to learn was a great   5    for me to do my best in school. We were always     6    with each other, trying to bring home the better grade.
When he turned 80 and still had a full head of hair, my grandfather felt like he could take on the       7   . He felt like he could beat the unstoppable no matter what came in his way---whether it was his continuing with cancer     8  a tough professor.
Some people look to Superman or Batman as their   9   , but my grandfather will forever be my hero, the      10   who always came to my rescue. My grandfather was made the hall of fame(名人堂) at his high school as one of the school’s most successful football players. When I did some research I   11 that his nickname was Atlas. In Greek mythology(神话), Atlas held the heavens on his shoulders. For my grandfather’s football team, he was 12 Atlas, holding the team together. He was my Atlas too, as the foundation of our family.
In my times of need he was always there to    13     me and celebrate my accomplishments. I could count on him to help me out and stand by me. The strength he 14    with me will continue to hold me up as I forever keep his memory    15   in my heart and mind.

D．grandfather

单项选择题

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