能使混凝土显著地减少拌合用水的掺加剂为缓凝剂。
参考答案：错
河姆渡人和半坡人都会做的是
①建造房屋② 制作磨制石器③种植粟④饲养家畜[ ]
A．①②③④
B．②④
C．①③④
D．①②④
No other item in a newspaper provides such entertaining reading or offers such deep insight into human nature.
