在地球形成之初，地球水就以蒸气的形式存在于炽热的地心中，或者以结构水、结晶水等形式存于地下岩石中。那时，地表的温度较高，大气层中以气体形式存在的水分也较多。地球在最初的5亿年，火山众多且活动频繁，大量的水蒸气通过火山口喷发出来，冷却之后便渐渐形成河流、湖泊和海洋，即所谓的“初生水”。下列对“初生水”表述准确的一项是（）。
A．存在于炽热地心中的水蒸气
B．存在于地下岩石中的结构水、结晶水
C．大气层中以气体形式存在的水分
D． 由火山喷发的水蒸气冷却后形成的水
参考答案：D
解析：由文段最后一句对“初生水”所作的定义，可知D选项正确。
| 阅读下列短文，选择可以填入空白处的最佳选项。 | ||||
| Last winter vacation, I visited Murdoch School in Australia with my parents. It was a beautiful school. 1 the attraction for me was that life at the school was quite relaxing. The students didn’t have 2 schoolbags. The teachers there said classes were from 8 am to 3 pm on weekdays. That means the students 3 only six hours a day for study (one hour for lunch). The teachers don’t 4 too much homework, so the students can 5 themselves on weekends or during winter and summer holidays. But in China, we have to study all the time. Usually, we have to get up at 6 o’clock in the morning and then study 6 10 o’clock at night. There is too much homework for 7 to finish after school. 8 all this, our schoolbags are extremely heavy with many textbooks, reference books, notebooks, and exam papers. Long hours of study and too much homework 9 most of us wear glasses. With light schoolbags, students enjoy school life; with heavy schoolbags, school life does not 10 students anymore. Of course, I really want the former (前者), but who can give it to me? | ||||
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