题目

上海师大附中等六校2011届高三联考英语试题 The fashion designer makes frequent trips to Paris, as it is street ahead_________fashion is concerned．        A．which       B．where       C．why  D．whose 答案：B0.5mol CO和CO2混合气体质量为18g，求混合气体中CO和CO2物质的量之比．