All students need to have good study habits(习惯). When you have good study habits, you can learn things quickly. You also remember them easily. Do you like to study in the living-room? This is not a good place because it is usuallytoo noisy. You need to study in a quiet place, like your bedroom. A quiet place will help you only think about one thing, and you will learn better. Before you begin to study, do not forget to clean your desk. A good desk light is important, too. You are feeling tired easily if there is not enough(足够的) light.

下列疾病中，不属于遗传病的是（    ）

如图，在平面直角坐标系中放置一个边长为1的正方形ABCD，将其沿x轴的正方向无滑动地在x轴上滚动，当点A离开原点后第一次落在x轴上时，点A运动的路径与x轴围成的面积为（   ）