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【单选题】
紫外线由紫外灯管提供，波长在200-295nm紫外线具杀菌能力，波长在（ ）nm左右的杀菌能力最强。
A.
245
B.
255
C.
260
D.
280
参考答案：
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