Dinosaurs now are far away from us. Dinosaurs were real animals that once lived on the earth, but they _1_ (die) out about 65 million years ago. The _2_(disappear) of the dinosaurs is _3_ some way a great mystery. Some scientists think that the climate changed suddenly. Fossils of trees tell us that the temperature dropped a lot and that the level of the sea dropped as well. This means that it got suddenly much _4_ (cold). Perhaps the dinosaurs were too slow __5__(change) with the climate. A new idea is _6_ a meteor(流星) crashed into the earth. Scientists discovered a place in Mexico _7_ they think the meteor crashed. They think that there was a lot of dust from the meteor. The dust landed on the plants. Also the dust blocked(阻挡)the sun’s light for as long as five years. Many animals, _8_ (include) dinosaurs, were plant eaters, and perhaps the dust killed __9___. This means there was nothing left for meat eating dinosaurs to eat, and so they died out. But, as many animals from that time did not die, we are not 100% sure what ___10__ (real) happened.
中官能团的名称 。
多一个碳的同系物，则满足下列条件的D的同分异构体共有 种，写出一种满足条件且含4种不同氢原子的同分异构体的结构简式 。
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