碱集料反应
参考答案：
水泥水化所析出的KOH和NaOH与集料中活动二氧化硅相互作用，形成了碱的硅酸盐凝胶，致使混凝土开裂即形成所谓碱集料反应.
The boy ______ his mistake before his teacher told him.[ ]
A. realizes
B. has realized
C. had realized
D. would realize
简答负荷管理系统为什么要建立中继站？
