se buildings increase the friction on air flowing around them。 This friction tends to slow the speed of winds； making them far less efficient at dispersing pollutants。 On the other hand； air turbulence increases because of the effect of skyscrapers on airflow。 Rainfall is also increased in cities。 The cause appears to be in part greater turbulence in the urban atmosphere as hot air rises from the built…up surface。
Question： Cities create climatic conditions of their own through their physical structure and urban activities。
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Answer Choices
1。 The amount of heat produced in a city will be reduced when cities use the heat from cars to warm houses。
2。 The built up landscape of the city readily bees a heat island； with greater water runoff and special climatic conditions such as low relative humidity and increased air turbulence。
3。 The materials from which cities are built and the effects of pollution domes help make urban areas warmer than rural areas。
4。 Cities tend to be warmer than their surrounding areas； in part because they produce heat by burning fuel for heating； powering vehicles； and industrial production。
5。 In most cities； the heating that results from solar radiation is intensified by carbon dioxide； a gas that is present at very high concentrations in cities’ atmospheres。
6。 During periods without rainfall； the air in cities heats up and causes winds to slow down with the result that pollutants are not dispersed。
閱讀題幹，可以知道題目要求選出符合“城市自身結構和城市活動會形成其自身的氣候條件”這一說法的選項。
觀察選項，第一項的意思是“城市產生的熱量會受因汽車的使用等因素影響”，而這只是支援“城市活動會影響氣候”這一觀點的一個細節，沒有概括地談及氣候的形成，因此不符合題意；
第二項主要講的是“城市地貌特徵很容易形成熱島”，是對文章最後兩段的總結，因此符合題意；
第三項講的是“城建材料和汙染會使城市比農村更溫暖”，是文章第三段提到的“兩個影響氣候的因素”的其中一個，因此