We should see the events in their historical ________ before we draw any conclusion.
A respective
B retrospective
C prospective
D perspective
钢管或球墨铸铁管道变形率应不超过3%,化学建材管道变形率应不超过2%。()
How many syllables does the word "middle" have?
A. 1.
B. 2.
C. 3
D. 4
醑剂中药物浓度一般为()
A. 5%~10%
B. 20%~30%
C. 30%~40%
D. 40%~50%
E. 60%~90%