单项选择题
A.活结每m2=3个、死结每m2=2个 B.活结每m2≥3个、死结每m2≤2个 C.活结每m2≤3个、死结每m2＞2个 D.活结每m2≤3个、死结每m2≤2个
A.-300-300℃ B.-50-200℃ C.-50-500℃ D.100-300℃
A.低于1% B.低于0.3% C.低于0.1% D.低于0.2%