下列无机非金属材料中，属于硅酸盐材料的是[ ]
①光导纤维②氮化硅陶瓷③人造刚玉④水泥⑤玻璃
A．②④
B．④⑤
C．①②③
D．①②⑤
答案：B
This year the farmers were just able to gather in the _____ before the fine weather came to an end.
A．collection
B．harvest
C．flower
D．plant
组织细胞缺损后由损伤周围的同种细胞来修复，称为
A．修复
B．增生
C．再生
D．创伤愈合
E．化生
