北京、上海高新技术产业发达,主要原因是这里[ ]
A.原料丰富
B.人口稠密
C.环境优美
D.科学技术发达
答案:D
place do you prefer to live in, a big city or a small village?[ ]
A. Where
B. Which
C. How
D. Why
骨髓活检术的适应证有哪些