阅读下面短文，掌握其大意，然后从36—55各题所给的四个选项（A、B、C和D）中，选出最佳选项，并在答题卡上将该项涂黑。

    Every day, I drive home along Colorado Blvd, a wide street with four lanes on each side of the median (中央分隔带护栏). I always notice a homeless man standing on the corner of Colorado Blvd, 1 for spare change with a sign in his hand.
Last Monday, when I was 2 him, he suddenly threw down his sign and rushed into the middle of the street. At this time I 3 a car moving across the 3 lanes of traffic and heading for the  median. The 4 man ran to the side of the car and attempted to push the car back in the right 5. He also knocked on the window of the vehicle, but all  6 Immediately, he ran across the small median into four lanes of oncoming traffic, 7 madly for the cars to stop. Thankfully, all speeding cars 8 to stop just in time to 9 hitting him. The car which was out of 10 came Moving across the median and the four lanes of traffic, where just seconds ago cars had been traveling with 11 speeds.
    The homeless man jumped back in front of the 12 to attempt slowing it down again. By this time, we were able to 13 and help the man stop the car 14 it ran into a supermarket on the other side of the road. As it 15 out, the woman driver had a heart attack while driving and became 16 in the front seat.
    The homeless man is indeed a hero. He spends every day getting 17 by people who are trying not to make 18 contact with him so that they don't feel bad not giving him money. Yet he didn't  even hesitate to risk his life to save this lady and other drivers who would have 19 into her. He didn't think of his safety, nor did he expect anything in return. Heroes do exist in the most 20 places.

蛋白质、纤维素、蔗糖、PVC、淀粉都是高分子化合物　　（判断对错）

据史书记载，南宋时期太湖洞庭山区“地方共几百里，多种柑橘桑麻，糊口之物，尽仰商贩”。这反映了南宋时期该地区（    ）

    A．一次，小明看到了一群蚂蚁，发现有一群蚂蚁正在往洞里运食物。观察思考后，小明提出了一个问题：

    B．根据一段时间的观察和自己已有的知识和生活经验，他提出了许多假设：蚂蚁可能爱吃甜的食物，可 能爱吃软的食物，可能爱吃小昆虫。

    C．小明针对“蚂蚁爱吃甜的食物”这一假设，设计了一个实验：在一个培养皿的两端分别放上少许盐和 少许糖，把一只蚂蚁放进培养皿中，仔细观察蚂蚁的行为。

    D．小明按照实验设计完成了实验。

E．经过几次重复实验后，得出了结论：“蚂蚁爱吃甜的食物”。

F．然后他把探究过程和结果与同学进行了交流。