硅酸盐水泥
参考答案：凡由硅酸盐水泥熟料、0%~5%的石灰石或粒化高炉矿渣、适量石膏磨细制成的水硬性胶凝材料称为硅酸盐水泥，也称为波特兰水泥。
— You look nice in your new dress! When did you buy it?
—Don’t you know? I ______it for several days.
A. bought B. have bought C. have had
病毒衣壳的主要组成部分是
A．多糖
B．核酸
C．磷壁酸
D．脂质
E．蛋白
