1987年2月,美国华裔科学家朱经武和中国科学家()把临界超导温度提高到90K以上,突破了液氮(77K)的禁区?
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()科学家昂内斯在温度下降到4.2K时发现水银的电阻完全消失的超导现象?
A.英国
B.美国
C.荷兰
D.法国
第二代复合材料指的是?
A.碳纤维增强高分子基复合材料
B.硼纤维增强高分子基复合材料
C.玻璃纤维增强高分子基复合材料
D.晶须增强高分子基复合材料
Little _______ about her own safety, though she herself was in geat danger.
A. she cared
B. she may care
C. may she care
D. did she care
The couple hed no soner got to the staton _______ the coach left.
A. when
B. as
C. until
D. than