All the planets in the solar system have an atmosphere _____36_____ some extent. An atmosphere is a layer of gas _____37_____ a world. In general, it is an extremely thin layer. In the case of the Earth, _____38_____ , approximately two-thirds of the air in the atmosphere _____39_____ within 10 kilometers of Earth's surface. In other words, this air is only as thick as a dollar bill if represented on a standard globe. The air that makes up any atmosphere is a mixture of several types of gases that consists either of individual atoms _____40_____ of molecules. In most cases, temperature in the atmospheres are low enough for atoms to combine into molecules. The air we breathe, for instance, consists of molecular nitrogen and oxygen as opposed to individual atoms. 【題組】38. (A) for example (B) in contrast (C) on one hand (D) in sum
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