________ so many people around, it wasn't convenient to have a long talk with him.
As
B. When
C. With
D. Since
岩溶与土洞地基的防治方法有()
A. 挖填
B. 跨盖
C. 灌注
D. 排导
制备DNS-氨基酸时,反应液的pH值应该调至哪个范围?()
A. 5.5-7.5
B. 6.0-9.0
C. 7.5-9.5
D. 9.0-10.5
侵蚀作用包括()
A. 动物侵蚀
B. 机械侵蚀
C. 化学溶蚀
D. 生物溶蚀