题目

Americans with small families own a small car or a large one. If both parents are working, they usually have two cars. When the family is large, one of the cars is sold and they will buy a van（住房汽车） A small car can hold（容纳）four persons and a large car can hold six  persons but it is very crowded（拥挤）.A van hold seven persons easily, so a family three children could ask their grandparents to go on a holiday travel. They could all travel together.     Mr. Hagen and his wife had a third child last year. This made them sell a second car and buy a van. Their children禁止青少年吸烟是因为（ ）A.烟内含激素，吸放后影响正常发育B.烟内含有害物质，吸入后对呼吸道有害C.烟内含有能让人兴奋的物质D.烟内含抑制大脑活动的物质，吸入后会反应迟钝