黏土和石灰石高温煅烧后再加入适量的石膏磨成细粉,所得的产品是( )
①水泥②玻璃③瓷器④混凝土⑤一种硅酸盐.
A:①②
B:①⑤
C:③
D:②
The old man______ the street when he was hit by a car.