下图是我国发行的邮票《古代科学家——贾思勰》,他的成就是著有
A.《水经注》
B.《齐民要术》
C.《伤寒杂病论》
D.《九章算术》
答案:B
非均质体矿物在正交偏光镜下旋转360°会出现()的现象。
The objective of shoring a damaged bulkhead is to().
A.force the warped, bulged, or deformed sections back into place
B.support and hold the area in the damaged position
C.withstand subaequent additional damaged
D.make a watertight seal at the damaged area