题目

阅读下面材料，根据其内容和所给段落开头语续写两段，使之构成一篇完整的短文。WHAT KEPT THE NEW CHIMNEY(烟囱) WAITINGA new chimney was going to be built on Grandpa's house, and the boys were in a state of great excitement. They were always excited when something was going on. “This would be splendid,” Wayne said.“Mike is coming, you know, to mixthe mud and carry it up the ladder to the builder. He will tell us stories inthe mornings,” Wayne told Casper.“Yes,” said Casper, “and, Wayne,let's go get his tools and play we are his helpers, carrying h在建筑工地上有时需要将一些建筑材料由高处送到低处，为此工人们设计了一种如图所示的简易滑轨：两根圆柱形木杆AB和CD相互平行，斜靠在竖直墙壁上，把一摞弧形瓦放在两木杆构成的滑轨上，瓦将沿滑轨滑到低处，在实际操作中发现瓦滑到底端时速度较大，有可能摔碎，为了防止瓦被损坏，下列措施中可行的是( )A. 增多每次运送瓦的块数B. 减少每次运送瓦的块数C. 减小两杆之间的距离D. 增大两杆之间的距离