正确答案: C

聚乙烯

题目：材料的应用和发展与人类文明的进步紧密相关，下列材料属于有机合成材；

解析：C

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学习资料的答案和解析：

[单选题]London-is such a wonderful city．It is very large．The Thames River runs (11) the city from west to east． So the city has (12) parts: the South and the North． In the North， there are important buildings， shops， big parks and interesting places． the weather in London is good． In winter it is not very cold and in summer it is not very hot (13) the city is near the sea． People say (14 ) London is a foggy city and it often rains． It is true．Last year，when l (15) in London， Imet one of the (16) fogs in years． You could hardly see your hands in front of your face． Cars and buses moved -along with their lights on．When evening fell， the weather (17 ) even worse． The fog was as thick as milk．(18) the buses and cars stopped． I happened (19 ) ． an important meeting on the other side of the town， but it was impossible to find a car． I had to get there (20) ．

( )11．

through

[单选题]某工地发生多人食物中毒，经化验为误食工业用盐亚硝酸钠（NaNO2）所致。NaNO2中氮元素的化合价是（        ）

+3