某住宅楼为7层混合结构，采用混凝土小型砌块，墙体加构造柱，为防止裂缝墙体中设拉接筋。外墙勒角及地面采用石材装饰。
根据以上情况，请回答下列问题：
下列选项中，关于石材的描述正确的是( )。
A．石材的表观密度与矿物组成及孔隙率有关
B．土木工程中使用的石材软化系数应大于0.8
C．一般吸水率大的石材，抗冻性能差
D．表面密度大的石材，吸水率也大
E．测定岩石抗拉强度需要的试件尺寸为50mm2的立方体
参考答案：A,B,C
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| China's Liu Xiang has shown that he is one ofthe world's 1 men! In the 28th Olympics,Liu Xiang _2 the 110-metre hurdles with 12. 91 seconds. It's as fast as the world record,and the best ever in the Olympics! It was the first men's athletics gold for China in the Olympics. "I 3 Asians can run fast,too," he said. Liu loved sports _4 he was a child in Shanghai. "He kept running and jumping every day. He never sat there _5_,"said his mother. In the fourth grade,Liu tried high jump. He was always the first to try a higher jump. He would jump until he 6 it! But people said he was not 7 enough. "I told my mother that I wanted to be in theOlympics," Liu said. Luckily, at the age of 15, Liu 8 his coach Sun Haiping. Sun thought he could be No. 1 in the 110-metre hurdles.He was right. But young people love Liu not just for his sporting talent (才能) , _9 for his fashion (时尚).He likes singing with his friends. He sings like a karaoke star.He likes to make fun of his pimples (痘) on his face, "I would be better-looking i fl 10 them." | ||||
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