题目

Is human blood all the same? “Yes．” You may say．“It’s all red．” Well，it’s not as simple as you might think． Blood is made up of different parts，such as red blood cells（红血球），white blood cells and platelets（血小板）． Two chemical molecules（分子）on the red blood cells make people’s blood different．Scientists mark one molecule “A” and the other molecule “B”．According to which and how many molecules are on the red cell，scientists divide blood into four types：A，B，AB and O． Your blood type will stay the same all your life和大多数物质一样，汽油也有热胀冷缩的性质，随着气温上升，汽油的密度会__________（选填“变大”或“变小”），受此因素影响，在每吨汽油价格不变的情况下，夏季每升（每立方分米）汽油的价格应比冬季的价格__________（选填“上调”或“下调”）．气温升高时，汽油的内能是通过__________方式改变的。 变小 下调 热传递 【解析】随着气温的上升,汽油的体积变大,在质量不变的情况下,根据公式ρ＝可知密度变小；根据公式m＝ρV可知，相同体积的汽油质量减少，所以每升汽油价格下调。气温升高时，汽油的内能是通过热传递方式改变的。