要求空气清洁的房间,室内应保持()压,放散粉尘或有害气体或有爆炸危险物质的房间,应保持()压。
查看答案
在筛选营养缺陷型菌株时,若将诱变后的酵母或霉菌培养在含有制霉菌素的基本培养基中,为什么能达到淘汰野生型和浓缩缺陷型的目的?
二氧化硫排放量增长最快的地区是()
A. 北美
B. 南美
C. 东亚
D. 欧洲
A vessel which through some exceptional circumstance is unable to maneuver as required by these Rules and is therefore unable to keep out of the way of another vessel is called().
A. a vessel restricted in her ability to maneuver
B. a vessel not under command
C. a vessel engaged in fishing
D. a vessel constrained by her draught