汽车沿平直公路从甲地开往乙地，两地相距90km，开始时汽车以10m/s的速度行驶了1.5h，然后余下的路程要在45min内匀速行驶完，求：后来汽车应以多大的速度行驶？

下列运算正确的是（　　）

我国的一个省级区域自然地理特征是：地形以山地为主，山脉呈南北纵列分布，气候湿热，河流短小水急，植物种类丰富。据此判断这个省级行政区为（    ）

C

    Do you have brown hair? Are you taller than other kids your age? These characteristics were decided before you were born. You got your traits from your parents. They passed their traits on to you through genes (基因).

    Genes carry codes (代码) for blue eyes or brown eyes. Genes say how tall you will get and what color hair you will have. You got half of your genes from your mother. You got half of your genes from your father. So you have your own set of genes. Each person gets different genes for each body part. That is why you look like but not exactly like your brother or sister.

    A dominant (显性的)  gene shows up most of the time. Brown eyes are dominant over bluc eyes. A recessive (降性的)  gene shows up less often. Light hair comes from a recessive gene. Dark hair is more common. Look at the eye color and hair color of the people around you. You will see that this is true.

    Genes help to make you who you are. But they don't tell the whole story. Your genes may help you to be fast and strong. But you still need to learn how to run or swim or skate well.