题目

（2010·山东聊城一中高三模块测试）      29．She showed us the whole dance first, then _________so that we could learn it more easily． A．got it through B．carried it out   C．broke it down D．took it over 答案：C一段长4分米的长方体钢材，它的横截面是边长4厘米的正方形，如果每立方厘米的钢重7.8克，钢材的重量是多少克？