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参考解析：
刷刷题刷刷变学霸
举一反三
【单选题】Space is a dangerous place, not only because of meteors (流星) but also because of rays from the sun and other stars. The atmosphere again acts (67) our protective blanket on (68) . Light gets through, ...
A.
from
B.
than
C.
as
D.
away
【单选题】45号钢经调质后的对称循环疲劳极限σ-1＝307 MPa，应力循环基数N0＝5×106次，疲劳曲线指数m＝9，当实际应力循环次数N＝106时，有限寿命的疲劳极限σ-1N为( )MPa。[同济大学2010研]
A.
257
B.
367
C.
474
D.
425