题目

X、Y、Z为三种气体，把a mol X和b mol Y充入一密闭容器中，发生如下反应：X+2Y2Z。达到平衡时，若它们的物质的量满足n(X)+n(Y)=n(Z)，则Y的转化率为（    ） A.×100%     B.×100%      C.×100%     D.×100% 答案：B 解析:设X的转化量为W。         X  +  2Y2Z 起      a      b      0 转      W      2W     2W 平      a-W    b-2W   2W 由题意得： a-W+b-2W=2W W= mol Y的转化率为： ×100%=×100%Mike was the despair(绝望) of his parents. In many ways, he was a model child. He was well-behaved and polite. He did well in math and science. However, the reason for his parents’ despair was that Mike would not ____ , not even a magazine. His parents had asked his teacher for advice on how to make Mike read. They had taken him to the local library and shown him all the different types of books. For his birthday, they bought him books with bright covers. He took no ______ of them. His favorite aunt presented him with an exciting video as his birthday present. The video was based on a well- known _____. Mike would watch the video and talk about it for days. But when his aunt suggested that he might like to read the book, Mike would lose all his ___ . Whenever Mike got facts wrong, the rest of the family laughed at him, “Oh, Mike! You know nothing! All because you won’t read books.”But there came one momentous(重要的) day when Mike returned home with a book. He ___it under his shirt trying to take it into the house secretly. His keen-eyed sister noticed it. It was she who discovered how Mike had come to take an interest in reading. Unknown to the family, Mike had often made _____ trips to the library. There, he had taken part in some activities. At one meeting, Mike listened to a speaker talk about the excitement of reading science fiction. The talk_____ Mike’s life. From that moment on, his head was always buried in a book. When books were opened, Mike discovered that he had wings. Science fiction at first, but, as his ___ broadened, he read widely. His parents were amazed at the change in Mike and wondered what had persuaded him to read.【1】A. listenB. speakC. writeD. read【2】A. photosB. noticeC. chanceD. notes【3】A. bookB. movieC. personD. program【4】A. wayB. faceC. breathD. interest【5】A. hidB. leftC. feltD. found【6】A. shortB. braveC. secretD. different【7】A. decidedB. changedC. startedD. made【8】A. planB. roleC. tasteD. promise