题目

NA表示阿伏加德罗常数，下列叙述正确的是A. 1molFe在1molCl2中充分燃烧，转移的电子数目为3NAB. 2.3gNa和足量O2完全反应，在常温或燃烧时，转移电子数均为NAC. 在常温常压下，14g由N2和CO组成的混合气体含有的原子数目为NAD. 20℃、101KPa，22.4 L氯气与足量镁粉充分反应，转移的电子数为2NA 答案：【答案】C【解析】A项，1mol铁完全反应生成氯化铁需要消耗1.5mol氯气，所以氯气不足，转移的电子应按氯气来计算，1molCl2完全反应得到2mol电子，转移的电子数为2NA，故A错误；B项，Na和足量O2完全反应，在常温或燃烧时，均生成+1价钠的化合物，2.3gNa物质的量是0.1mol，转移电子数为0.1NA，故B错误；C项，That day I was later for school, so Mom offered me a   36 . I sat beside her in our car, daydreaming about my  37 . I’d be graduating from high school in a few months. I’d leave high school behind and do whatever I wanted. What  38 I do? Go to college? Or get a job in an office where I could  39 my way up?Mom interrupted my thoughts.“Kassandra, do you  40  that?’’She asked just as we were  41  the railroad tracks. She stopped the car on the other side and   42  the window. “It looks like a child.’’  43 ,I saw a small boy walking by himeself. The warning lights on the train tracks flashed  44 .The boy stayed where he was right in the middle of the   45 .The whistle sounded. There’s no  46  that train can stop in time!The boy jumped up and down and   47  at the engineer.I took off running. My shoes flopped(松动) against my feet as I   48 , so I kicked them off. I ran faster. Stones crunched(发出刺耳的碎裂声) and flew under my   49  feet. The ground shook. God, let me get to him! The train was almost on top of him. I   50 the boy in my arms. Keep running! But something   51  me. I fell backward, away from the train. I pulled the boy with me onto safe ground. The train barreled(高速行驶)past. The noise was  52 . The wheels were so close that I could have reached out and touched one. Once the train was out of  53 , I stood up. Mom ran up and hugged me. “Kassandra, I didn’t think you were going to  54 it !’’ I got ready for bed that night  55 looking forward to school the next day. I wanted to enjoy every moment in life.小题1:A．helpB．favorC．handD．ride小题2:A．loveB．futureC．jobD．university小题3:A．wouldB．shouldC．couldD．might小题4:A．walkB．struggleC．feelD．work小题5:A．seeB．hearC．watchD．find小题6:A．passingB．repairingC．crossingD．building小题7:A．brought downB．rolled outC．pointed outD．looked out小题8:A．At lengthB．Frankly speakingC．After allD．Sure enough小题9:A．redB．yellowC．greenD．black小题10:A．streetsB．trainC．tracksD．roads小题11:A．possibilityB．problemC．wayD．doubt小题12:A．shotB．wavedC．shoutedD．laughed小题13:A．ranB．droveC．thoughtD．walked小题14:A．bigB．bareC．fastD．quick小题15:A．drewB．heldC．ledD．caught小题16:A．attractedB．knockedC．struckD．pushed小题17:A．deafeningB．soundingC．excitingD．loud小题18:A．fashionB．mindC．sightD．date小题19:A．fetchB．doC．makeD．get小题20:A．thusB．alreadyC．neverD．still