对于恒容密闭容器中一定条件下的反应：N2+3H2⇌2NH3，下列说法正确的是（ ）
A．增加N2的量，可以加快反应速率
B．当N2和H2全部转化为NH3时，反应达到最大限度
C．达到平衡时，H2和NH3的浓度比一定为3：2
D．分别用N2和NH3来表示该反应的速率时，数值大小相同
A．增大反应物的浓度，反应速率加快，则恒容时增加N2的量，氮气的浓度增大，可以加快反应速率，故A正确；
B．可逆反应中不能完全转化，则N2和H2不能完全转化为NH3，浓度不变时达到转化的最大限度，故B错误；
C．平衡时，物质的浓度关系取决起始量和转化率，所以到平衡时，H2和NH3的浓度比不一定为3：2，故C错误；
D．反应速率之比等于化学计量数之比，因化学计量数不同，则反应速率的数值不同，故D错误；
故选A．
Denny Crook was a famous photographer(摄影师). He traveled all over the world, taking pictures for magazines and newspapers, and won many prizes. “I’ll do anything to get a good photo,” he often said. “I’ll go anywhere at any time, even if it is 41 .” And he told the 42 .He had photos of earthquakes, forest fires, floods and even wars. If something interesting happened, Denny went to photo it. He was a married man and his wife often asked him to take her with him, but he always 43 . “I’ll travel for my work, not for 44 ,” he told her. “You won’t enjoy yourself, and I won’t have 45 to look after you. Sometimes there’s not even anywhere to 46 ,and I have to sleep outside. I often don’t have a good 47 or a bath for days. You won’t like it.” “Denny, I’m not a child,” his wife didn’t 48 . “I can look after myself. Please take me with you the next time you go overseas.” Denny did not say anything, but he 49 about it, and when he was asked to go to Africa he said to his wife,” You can come to Africa with me if you want to. I’ve got to take photos of wild 50 there. It should be interesting and not too uncomfortable.” His wife was very 51 ,and at first she had a very enjoyable time. Then Denny went off to 52 some lions to photo. His wife went with him, but before long they became separated(分开).She walked down one path while he walked down the other. Suddenly, Denny heard her 53 .He ran back and saw her running toward him. A huge lion was chasing her. Quickly Denny took his camera out of its case and 54 it at his wife and the lion. Then he shouted, “ 55 ,woman !I can’t get you both in the picture!”
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