某封冻的河面上的冰能承受的最大压强是4×10⁴Pa，在冰面上行驶的小车质量是200kg，它与冰面的接触面积是0.4m²．在保证安全的情况下，小车上最多能装多大质量的货物？取g=10N/kg．

阅读下列短文，从下面每小题的A、B、C、D四个选项中选出最佳选项。

    A group of eight students from Shenzhen Middle School won the gold medal at the 2017 United States International Youth Physics Competition on January 31. It was the second time for the school to win the prize after its first championship in 2013.

    All of the open-ended projects studied at the competition are beyond the normal standard at high schools. Shenzhen Middle School is the only high school in China that has won the gold medal.

    The competition this year attracted 11 top high schools in the United States and China, including Harker School and Philips Exeter University in the United States as well as the Middle School Affiliated with Renmin University of China（人大附中）and Nanjing Foreign Languages School in China.

    The Shenzhen Middle School team went through a two-day debate with the other teams in English about four physics projects that they had studied for a whole year.

The school said that the team prepared for a whole year, from raising theoretical（理论） models to designing experiments, which greatly developed the students' abilities to work and think like real scientists.

在“比较不同物质吸热升温情况”的实验中：

材料一：对列宁而言，新经济政策并不意味着社会主义在俄国的结束，而只是一次暂时的退却，“后退一步为的是前进两步”                   

---- 斯塔夫里阿诺斯《全球通史》

材料二：　我们的首要任务是给人们工作。只要我们明智而勇敢地对待它，这并不是无法解决的问题。这个任务通过政府直接征募人员可以得到部分完成，就像我们应付战时紧急状态那样，同时通过雇用这些人员来完成急需工程，以促进和改革我们对自然资源的利用。……要把目前常常是分散、浪费和不公平的救济工程统一起来。

　　　　　　　　　　　　　　　　　——罗斯福总统第一次就职演说

材料三 全国工业总产值的所有制结构