下列现象中与静电有关的是( )
| A．用塑料梳子梳干燥的头发，越梳越蓬松 |
| B．通信卫星采用硅光电池板提供电能 |
| C．运送石油的大卡车常在地上拖一条铁链 |
| D．晚上脱化纤毛衣时会有火花产生 |
二茂铁[(C5H5)2Fe] 分子是一种金属有机配合物，是燃料油的添加剂，用以提高燃烧的效率和去烟，可作为导弹和卫星的涂料等。它的结构如图所示，下列说法正确的是
| A．二茂铁中Fe2+与环戊二烯离子（C5H5-）之间为离子键 |
B．1mol环戊二烯（ ）中含有σ键的数目为5NA |
| C．分子中存在π键 |
| D．Fe2＋的电子排布式为1s22s22p63s23p63d44s2 |
二茂铁[(C5H5)2Fe] 分子是一种金属有机配合物，是燃料油的添加剂，用以提高燃烧的效率和去烟，可作为导弹和卫星的涂料等。它的结构如图所示，下列说法正确的是
| A．二茂铁中Fe2+与环戊二烯离子（C5H5-）之间为离子键 |
B．1mol环戊二烯（ ）中含有σ键的数目为5NA |
| C．分子中存在π键 |
| D．Fe2＋的电子排布式为1s22s22p63s23p63d44s2 |
二茂铁[(C5H5)2Fe] 分子是一种金属有机配合物，是燃料油的添加剂，用以提高燃烧的效率和去烟，可作为导弹和卫星的涂料等。它的结构如图所示，下列说法正确的是
| A．二茂铁中Fe2+与环戊二烯离子（C5H5-）之间为离子键 |
B．1mol环戊二烯（ ）中含有σ键的数目为5NA |
| C．分子中存在π键 |
| D．Fe2＋的电子排布式为1s22s22p63s23p63d44s2 |
有一种新型节能灯—LED灯，使用这种灯比旧灯泡节能90%，且发出光的颜色会随电压的变化而变化(见下表)．
(1)根据表中数据，求出当LED灯发出红光时，100 s消耗的电能是多少
(2)把一个LED灯接入如图所示的电路中，已知电源电压为5 V且保持不变，电阻R为90 Ω.闭合开关，毫安表(量程更小的电流表)的读数为20 mA，请你通过计算说明此时LED灯发出什么颜色的光？
| LED灯两端电压(V) | 通过LED灯电流(mA) | LED灯发现光的颜色 |
| 1.8 | 20 | 红 |
| 2.4 | 20 | 黄 |
| 3.2 | 20 | 蓝 |
(2)把一个LED灯接入如图所示的电路中，已知电源电压为5 V且保持不变，电阻R为90 Ω.闭合开关，毫安表(量程更小的电流表)的读数为20 mA，请你通过计算说明此时LED灯发出什么颜色的光？
Which came first, the chicken or the egg? This is one of life’s __1__ questions and people have been debating about it for thousands of years. Now scientists believe they have solved this _2__. Researchers from Sheffield and Warwick Universities in England discovered the answer __3__. They used a super computer to observe the shell-making process while a new shell was __4__. Then they found one protein called OC17 that is __5__ for forming eggshell. This is only found inside a chicken’s body, which is proof that the _6__ came first. The team was __7__ looking at how animals and birds make eggshells but suddenly made their surprising __8__. The big question now is where chickens came from. The _9__ is from dinosaurs.
The research team said eggshells are one of nature’s most __10__ creations. Professor John Harding from the team told reporters: “Understanding how chickens make eggshells is fascinating in itself, but it can also be __11__ in designing new materials.” Eggshells are very lightweight but incredibly strong. Even the most up-to-date materials __12__ by the world’s top engineers can not produce anything as __13__ as an eggshell. Professor Harding added that __14__ eggshells could help to cure bone diseases and design materials for the construction industry.“Nature has found wonderful ways that __15__ for all kinds of problems in materials science and technology — we can learn a lot from them.” he said.
0 65250 65258 65264 65268 65274 65276 65280 65286 65288 65294 65300 65304 65306 65310 65316 65318 65324 65328 65330 65334 65336 65340 65342 65344 65345 65346 65348 65349 65350 65352 65354 65358 65360 65364 65366 65370 65376 65378 65384 65388 65390 65394 65400 65406 65408 65414 65418 65420 65426 65430 65436 65444 235360
The research team said eggshells are one of nature’s most __10__ creations. Professor John Harding from the team told reporters: “Understanding how chickens make eggshells is fascinating in itself, but it can also be __11__ in designing new materials.” Eggshells are very lightweight but incredibly strong. Even the most up-to-date materials __12__ by the world’s top engineers can not produce anything as __13__ as an eggshell. Professor Harding added that __14__ eggshells could help to cure bone diseases and design materials for the construction industry.“Nature has found wonderful ways that __15__ for all kinds of problems in materials science and technology — we can learn a lot from them.” he said.
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